Pressure Sensor Constituting Plurality Of Channels, Touch Input Device Including Same, And Pressure Detection Method In Which Same Is Used

ABSTRACT

A touch input device capable of detecting a pressure of a touch on a touch surface may be provided. The touch input device includes: a display module; and a pressure sensor which is disposed at a position where a distance between the pressure sensor and a reference potential layer is changeable according to the touch on the touch surface. The distance is changeable according to a pressure magnitude of the touch. The pressure sensor outputs a signal including information on a capacitance which is changed according to the distance. The pressure sensor includes a plurality of electrodes to form a plurality of channels. The pressure magnitude of the touch is detected on the basis of a change amount of the capacitance detected in each of the channels and an SNR improvement scaling factor assigned to each of the channels.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

The present application is a U.S. national stage application under 35U.S.C. § 371 of PCT Application No. PCT/IB2016/051998, filed Apr. 8,2016, the disclosure of which is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

The present disclosure relates to a pressure sensor forming a pluralityof channels for pressure detection and a touch input device includingthe same, and more particularly to a pressure sensor which is applied toa touch input device configured to detect a touch position and forms aplurality of channels for detecting a touch pressure, the touch inputdevice including the same, and a pressure detection method using thesame.

BACKGROUND ART

Various kinds of input devices are being used to operate a computingsystem. For example, the input device includes a button, key, joystickand touch screen. Since the touch screen is easy and simple to operate,the touch screen is increasingly being used to operate the computingsystem.

The touch screen may constitute a touch surface of a touch input deviceincluding a touch sensor panel which may be a transparent panelincluding a touch-sensitive surface. The touch sensor panel is attachedto the front side of a display screen, and then the touch-sensitivesurface may cover the visible side of the display screen. The touchscreen allows a user to operate the computing system by simply touchingthe touch screen by a finger, etc. Generally, the computing systemrecognizes the touch and a position of the touch on the touch screen andanalyzes the touch, and thus, performs operations in accordance with theanalysis.

Here, there is a demand for a touch input device capable of detectingnot only the touch position according to the touch on the touch screenbut a pressure magnitude of the touch.

DISCLOSURE Technical Problem

The object of the present invention is to provide a pressure sensorforming a plurality of channels for pressure detection, a touch inputdevice including the same, and a pressure detection method using thesame.

Technical Solution

One embodiment is a touch input device capable of detecting a pressureof a touch on a touch surface. The touch input device includes: adisplay module; and a pressure sensor which is disposed at a positionwhere a distance between the pressure sensor and a reference potentiallayer is changeable according to the touch on the touch surface. Thedistance is changeable according to a pressure magnitude of the touch.The pressure sensor outputs a signal including information on acapacitance which is changed according to the distance. The pressuresensor includes a plurality of electrodes to form a plurality ofchannels. The pressure magnitude of the touch is detected on the basisof a change amount of the capacitance detected in each of the channelsand an SNR improvement scaling factor assigned to each of the channels.

Advantageous Effects

According to the embodiment of the present invention, it is possible toprovide a pressure sensor forming a plurality of channels for pressuredetection, a touch input device including the same, and a pressuredetection method using the same.

In addition, according to the embodiment of the present invention, it ispossible to provide the pressure sensor which has a high-pressuredetection accuracy of the touch and forms a plurality of channels, andthe touch input device including the pressure sensor.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a configuration of a capacitance typetouch sensor panel and the operation thereof;

FIGS. 2a to 2e are conceptual views showing a relative position of thetouch sensor panel with respect to a display panel in a touch inputdevice according to the embodiment;

FIGS. 3a to 3h are cross sectional views of an exemplary pressure sensorincluding a pressure electrode according to the embodiment of thepresent invention;

FIG. 3i is a view showing a capacitance change amount according to adistance change between an electrode layer and a reference potentiallayer according to the embodiment of the present invention;

FIG. 4a is a cross sectional view of the touch input device of a firstexample, to which the pressure sensor and pressure detection moduleaccording to the embodiment of the present invention can be applied;

FIG. 4b shows an optical layer of a backlight unit in the touch inputdevice according to the embodiment;

FIG. 4c is a cross sectional view of the touch input device of a secondexample, to which the pressure sensor and pressure detection moduleaccording to the embodiment of the present invention can be applied;

FIGS. 5a and 5b show a relative distance between the pressure sensor andthe reference potential layer of the first example included in the touchinput device and show a pressure is applied to the touch input device;

FIGS. 5c and 5d show a relative distance between the pressure sensor andthe reference potential layer of the second example included in thetouch input device and show a pressure is applied to the touch inputdevice;

FIG. 5e shows the arrangement of pressure sensors of a third example,which is included in the touch input device;

FIG. 6a is a cross sectional view showing a portion of the touch inputdevice to which the pressure sensor has been attached according to afirst method;

FIG. 6b is a plan view of the pressure sensor to be attached to thetouch input device in accordance with the first method;

FIG. 6c is a cross sectional view showing a portion of the touch inputdevice to which the pressure sensor has been attached according to asecond method;

FIGS. 7a to 7e show pressure electrode patterns included in the pressuresensor for pressure detection according to the embodiment of the presentinvention;

FIGS. 8a and 8b show a relation between a magnitude of a touch pressureand a saturated area in the touch input device to which the pressuresensor has been applied according to the embodiment of the presentinvention;

FIGS. 9a to 9d show cross sections of the pressure sensor according tothe embodiment of the present invention;

FIGS. 10a and 10b show an attachment method of the pressure sensoraccording the embodiment of the present invention;

FIGS. 11a to 11c show how the pressure sensor is connected to a touchsensing circuit in accordance with the embodiment of the presentinvention;

FIGS. 12a to 12d show that the pressure sensor according to theembodiment of the present invention includes a plurality of channels;

FIGS. 13a to 13c show forms of a first electrode and a second electrodeincluded in the pressure sensor according to the embodiment of thepresent invention;

FIG. 13d shows the form of the first electrode included in the pressuresensor according to the embodiment of the present invention;

FIG. 14a is a view showing that a pressure is applied to a predeterminedposition in the pressure sensor shown in FIG. 13 d;

FIG. 14b is a cross sectional view showing a form in which the touchinput device is bent when the touch pressure is applied to a touchsurface corresponding to a position “A” of FIG. 14 a;

FIG. 14c is a cross sectional view showing a form in which the touchinput device is bent when the touch pressure is applied to a touchsurface corresponding to a position “C” of FIG. 14 a;

FIG. 15 is a view showing a scaling factor assigned to each firstelectrode in the pressure sensor shown in FIG. 13 d;

FIG. 16a is a graph for describing, when the pressure is applied to theposition shown in FIG. 14a , a relation between a volume change amountof the touch input device and a magnitude of the applied pressure;

FIG. 16b is a cross sectional view showing the volume change amount ofthe touch input device shown in FIG. 14 b;

FIG. 16c is a cross sectional view showing the volume change amount ofthe touch input device shown in FIG. 14 c;

FIG. 17a is a partial perspective view for describing a form in whichthe touch input device is deformed when the pressure is applied to thetouch input device;

FIG. 17b is a view for describing the estimation of the volume changeamount of the touch input device when the pressure is applied to thetouch input device;

FIG. 17c is a cross sectional view of FIG. 17 b;

FIG. 18a shows an equivalent circuit of a device for sensing a pressurecapacitance of the pressure sensor having the forms shown in FIGS. 13ato 13 c;

FIG. 18b shows an equivalent circuit of a device for sensing thepressure capacitance of the pressure sensor shown in FIG. 13 d;

FIG. 19a is a view for describing a case where a pressure is applied toa position “D” in the pressure sensor shown in FIG. 14 a;

FIG. 19b is a graph for describing the calculation of a pressure valuewhen the pressure is applied to the position “D” shown in FIG. 19 a;

FIGS. 20a to 20c are flowcharts for describing examples of a method fordetecting the magnitude of the touch pressure by using a plurality ofchannels in the touch input device according to the embodiment of thepresent invention;

FIG. 21a is a graph showing an amplitude of a signal includinginformation on the capacitance detected in the channel corresponding tothe position “a” of FIG. 17 c;

FIG. 21b is a graph showing an amplitude of a signal includinginformation on the capacitance detected in the channel corresponding tothe position “b” of FIG. 17 c;

FIGS. 22a and 22b are views for describing an SNR improvement scalingfactor which is assigned to each channel when a pressure is applied to aposition “P”; and

FIG. 22c is a view showing capacitance change amounts detected in therespective channels when the pressure is applied to the position “P”.

MODE FOR INVENTION

The following detailed description of the present invention shows aspecified embodiment of the present invention and will be provided withreference to the accompanying drawings. The embodiment will be describedin enough detail that those skilled in the art are able to embody thepresent invention. It should be understood that various embodiments ofthe present invention are different from each other and need not bemutually exclusive. Similar reference numerals in the drawings designatethe same or similar functions in many aspects.

Hereinafter, a pressure sensor for pressure detection and a touch inputdevice to which a pressure detection module including the pressuresensor according to an embodiment of the present invention can beapplied will be described with reference to the accompanying drawings.Hereinafter, while a capacitance type touch sensor panel 100 isexemplified below, the touch sensor panel 100 capable of detecting atouch position in any manner may be applied.

FIG. 1 is a schematic view of a configuration of the capacitance typetouch sensor panel 100 which is included in the touch input device towhich a pressure sensor 440 and the pressure detection module includingthe pressure sensor 440 according to the embodiment of the presentinvention can be applied, and the operation of the touch sensor panel.Referring to FIG. 1, the touch sensor panel 100 may include a pluralityof drive electrodes TX1 to TXn and a plurality of receiving electrodesRX1 to RXm, and may include a drive unit 120 which applies a drivingsignal to the plurality of drive electrodes TX1 to TXn for the purposeof the operation of the touch sensor panel 100, and a sensing unit 110which detects whether or not the touch occurs and/or the touch positionby receiving a sensing signal including information on the capacitancechange amount changing according to the touch on the touch surface ofthe touch sensor panel 100.

As shown in FIG. 1, the touch sensor panel 100 may include the pluralityof drive electrodes TX1 to TXn and the plurality of receiving electrodesRX1 to RXm. While FIG. 1 shows that the plurality of drive electrodesTX1 to TXn and the plurality of receiving electrodes RX1 to RXm of thetouch sensor panel 100 form an orthogonal array, the present inventionis not limited to this. The plurality of drive electrodes TX1 to TXn andthe plurality of receiving electrodes RX1 to RXm has an array ofarbitrary dimension, for example, a diagonal array, a concentric array,a 3-dimensional random array, etc., and an array obtained by theapplication of them. Here, “n” and “m” are positive integers and may bethe same as each other or may have different values. The magnitude ofthe value may be changed depending on the embodiment.

As shown in FIG. 1, the plurality of drive electrodes TX1 to TXn and theplurality of receiving electrodes RX1 to RXm may be arranged to crosseach other. The drive electrode TX may include the plurality of driveelectrodes TX1 to TXn extending in a first axial direction. Thereceiving electrode RX may include the plurality of receiving electrodesRX1 to RXm extending in a second axial direction crossing the firstaxial direction.

In the touch sensor panel 100 according to the embodiment of the presentinvention, the plurality of drive electrodes TX1 to TXn and theplurality of receiving electrodes RX1 to RXm may be formed in the samelayer. For example, the plurality of drive electrodes TX1 to TXn and theplurality of receiving electrodes RX1 to RXm may be formed on the sameside of an insulation layer (not shown). Also, the plurality of driveelectrodes TX1 to TXn and the plurality of receiving electrodes RX1 toRXm may be formed in the different layers. For example, the plurality ofdrive electrodes TX1 to TXn and the plurality of receiving electrodesRX1 to RXm may be formed on both sides of one insulation layer (notshown) respectively, or the plurality of drive electrodes TX1 to TXn maybe formed on a side of a first insulation layer (not shown) and theplurality of receiving electrodes RX1 to RXm may be formed on a side ofa second insulation layer (not shown) different from the firstinsulation layer.

The plurality of drive electrodes TX1 to TXn and the plurality ofreceiving electrodes RX1 to RXm may be made of a transparent conductivematerial (for example, indium tin oxide (ITO) or antimony tin oxide(ATO) which is made of tin oxide (SnO₂), and indium oxide (In₂O₃),etc.), or the like. However, this is only an example. The driveelectrode TX and the receiving electrode RX may be also made of anothertransparent conductive material or an opaque conductive material. Forinstance, the drive electrode TX and the receiving electrode RX may beformed to include at least any one of silver ink, copper or carbonnanotube (CNT). Also, the drive electrode TX and the receiving electrodeRX may be made of metal mesh or nano silver.

The drive unit 120 according to the embodiment of the present inventionmay apply a driving signal to the drive electrodes TX1 to TXn. In theembodiment of the present invention, one driving signal may besequentially applied at a time to the first drive electrode TX1 to then-th drive electrode TXn. The driving signal may be applied againrepeatedly. This is only an example. The driving signal may be appliedto the plurality of drive electrodes at the same time in accordance withthe embodiment.

Through the receiving electrodes RX1 to RXm, the sensing unit 110receives the sensing signal including information on a capacitance (Cm)101 generated between the receiving electrodes RX1 to RXm and the driveelectrodes TX1 to TXn to which the driving signal has been applied,thereby detecting whether or not the touch has occurred and where thetouch has occurred. For example, the sensing signal may be a signalcoupled by the capacitance (CM) 101 generated between the receivingelectrode RX and the drive electrode TX to which the driving signal hasbeen applied. As such, the process of sensing the driving signal appliedfrom the first drive electrode TX1 to the n-th drive electrode TXnthrough the receiving electrodes RX1 to RXm can be referred to as aprocess of scanning the touch sensor panel 100.

For example, the sensing unit 110 may include a receiver (not shown)which is connected to each of the receiving electrodes RX1 to RXmthrough a switch. The switch becomes the on-state in a time intervalduring which the signal of the corresponding receiving electrode RX issensed, thereby allowing the receiver to sense the sensing signal fromthe receiving electrode RX. The receiver may include an amplifier (notshown) and a feedback capacitor coupled between the negative (−) inputterminal of the amplifier and the output terminal of the amplifier,i.e., coupled to a feedback path. Here, the positive (+) input terminalof the amplifier may be connected to the ground or a reference voltage.Also, the receiver may further include a reset switch which is connectedin parallel with the feedback capacitor. The reset switch may reset theconversion from current to voltage that is performed by the receiver.The negative input terminal of the amplifier is connected to thecorresponding receiving electrode RX and receives and integrates acurrent signal including information on the capacitance (CM) 101, andthen converts the integrated current signal into voltage. The sensingunit 110 may further include an analog-digital converter (ADC) (notshown) which converts the integrated data by the receiver into digitaldata. Later, the digital data may be input to a processor (not shown)and processed to obtain information on the touch on the touch sensorpanel 100. The sensing unit 110 may include the ADC and processor aswell as the receiver.

A controller 130 may perform a function of controlling the operations ofthe drive unit 120 and the sensing unit 110. For example, the controller130 generates and transmits a drive control signal to the drive unit200, so that the driving signal can be applied to a predetermined driveelectrode TX1 at a predetermined time. Also, the controller 130generates and transmits the drive control signal to the sensing unit110, so that the sensing unit 110 may receive the sensing signal fromthe predetermined receiving electrode RX at a predetermined time andperform a predetermined function.

In FIG. 1, the drive unit 120 and the sensing unit 110 may constitute atouch detection device (not shown) capable of detecting whether thetouch has occurred on the touch sensor panel 100 according to theembodiment of the present invention or not and/or where the touch hasoccurred. The touch detection device according to the embodiment of thepresent invention may further include the controller 130. The touchdetection device according to the embodiment of the present inventionmay be integrated and implemented on a touch sensing integrated circuit(IC, not shown) in a touch input device 1000 including the touch sensorpanel 100. The drive electrode TX and the receiving electrode RXincluded in the touch sensor panel 100 may be connected to the driveunit 120 and the sensing unit 110 included in the touch sensing ICthrough, for example, a conductive trace and/or a conductive patternprinted on a circuit board, or the like. The touch sensing IC may belocated on a circuit board on which the conductive pattern has beenprinted. According to the embodiment, the touch sensing IC may bemounted on a main board for operation of the touch input device 1000.

As described above, a capacitance (C) with a predetermined value isgenerated at each crossing of the drive electrode TX and the receivingelectrode RX. When an object like a finger approaches close to the touchsensor panel 100, the value of the capacitance may be changed. In FIG.1, the capacitance may represent a mutual capacitance (Cm). The sensingunit 110 senses such electrical characteristics, thereby being able tosense whether the touch has occurred on the touch sensor panel 100 ornot and where the touch has occurred. For example, the sensing unit 110is able to sense whether the touch has occurred on the surface of thetouch sensor panel 100 comprised of a two-dimensional plane consistingof a first axis and a second axis.

More specifically, when the touch occurs on the touch sensor panel 100,the drive electrode TX to which the driving signal has been applied isdetected, so that the position of the second axial direction of thetouch can be detected. Likewise, when the touch occurs on the touchsensor panel 100, the capacitance change is detected from the receptionsignal received through the receiving electrode RX, so that the positionof the first axial direction of the touch can be detected.

The mutual capacitance type touch sensor panel as the touch sensor panel100 has been described in detail in the foregoing. However, in the touchinput device 1000 according to the embodiment of the present invention,the touch sensor panel 100 for detecting whether or not the touch hasoccurred and where the touch has occurred may be implemented by usingnot only the above-described method but also any touch sensing methodlike a self-capacitance type method, a surface capacitance type method,a projected capacitance type method, a resistance film method, a surfaceacoustic wave (SAW) method, an infrared method, an optical imagingmethod, a dispersive signal technology, and an acoustic pulserecognition method, etc.

Hereinafter, a component corresponding to the drive electrode TX and thereceiving electrode RX for detecting whether or not the touch hasoccurred and/or the touch position can be referred to as a touch sensor.

In the pressure sensor and the touch input device 1000 to which thepressure detection module including the pressure sensor can be appliedaccording to the embodiment of the present invention, the touch sensorpanel 100 may be positioned outside or inside a display panel 200A. Thedisplay panel 200A of the touch input device 1000 according to theembodiment of the present invention may be a display panel included in aliquid crystal display (LCD), a plasma display panel (PDP), an organiclight emitting diode (OLED), etc. Accordingly, a user may perform theinput operation by touching the touch surface while visually identifyingan image displayed on the display panel. Here, the display panel 200Amay include a control circuit which receives an input from anapplication processor (AP) or a central processing unit (CPU) on a mainboard for the operation of the touch input device 1000 and displays thecontents that the user wants on the display panel. Here, the controlcircuit for the operation of the display panel 200A may be mounted on asecond printed circuit board (hereafter, referred to as a second PCB)(210) in FIGS. 10a to 12c . Here, the control circuit for the operationof the display panel 200A may include a display panel control IC, agraphic controller IC, and a circuit required to operate other displaypanels 200A.

FIGS. 2a to 2e are conceptual views showing a relative position of thetouch sensor panel 100 with respect to the display panel 200A in thetouch input device to which the pressure sensor 440 according to theembodiment can be applied. First, the relative position of the touchsensor panel 100 with respect to the display panel 200A using an LCDpanel will be described with reference to FIGS. 2a to 2 c.

As shown in FIGS. 2a to 2c , the LCD panel may include a liquid crystallayer 250 including a liquid crystal cell, a first substrate 261 and asecond substrate 262 which are disposed on both sides of the liquidcrystal layer 250 and include electrodes, a first polarizer layer 271formed on a side of the first substrate 261 in a direction facing theliquid crystal layer 250, and a second polarizer layer 272 formed on aside of the second substrate 262 in the direction facing the liquidcrystal layer 250. Here, the first substrate 261 may be color filterglass, and the second substrate 262 may be TFT glass. Also, the firstsubstrate 261 and/or the second substrate 262 may be a plasticsubstrate.

It is clear to those skilled in the art that the LCD panel may furtherinclude other configurations for the purpose of performing thedisplaying function and may be transformed.

FIG. 2a shows that the touch sensor panel 100 of the touch input device1000 is disposed outside the display panel 200A. The touch surface ofthe touch input device 1000 may be the surface of the touch sensor panel100. In FIG. 2a , the top surface of the touch sensor panel 100 is ableto function as the touch surface. Also, according to the embodiment, thetouch surface of the touch input device 1000 may be the outer surface ofthe display panel 200A. In FIG. 2a , the bottom surface of the secondpolarizer layer 272 of the display panel 200A is able to function as thetouch surface. Here, in order to protect the display panel 200A, thebottom surface of the display panel 200A may be covered with a coverlayer (not shown) like glass.

FIGS. 2b and 2c show that the touch sensor panel 100 of the touch inputdevice 1000 is disposed inside the display panel 200A. Here, in FIG. 2b, the touch sensor panel 100 for detecting the touch position isdisposed between the first substrate 261 and the first polarizer layer271. Here, the touch surface of the touch input device 1000 is the outersurface of the display panel 200A. The top surface or bottom surface ofthe display panel 200A in FIG. 2b may be the touch surface. FIG. 2cshows that the touch sensor panel 100 for detecting the touch positionis included in the liquid crystal layer 250, that is to say, the touchsensor panel 100 is disposed between the first substrate 261 and thesecond substrate 262. Here, the touch surface of the touch input device1000 is the outer surface of the display panel 200A. The top surface orbottom surface of the display panel 200A in FIG. 2c may be the touchsurface. In FIGS. 2b and 2c , the top surface or bottom surface of thedisplay panel 200A, which can be the touch surface, may be covered witha cover layer (not shown) like glass.

Next, a relative position of the touch sensor panel 100 with respect tothe display panel 200A using an OLED panel will be described withreference to FIGS. 2d and 2e . In FIG. 2 d, the touch sensor panel 100is positioned between a polarizer layer 282 and a first substrate 281.In FIG. 2e , the touch sensor panel 100 is positioned between an organicmaterial layer 280 and a second substrate 283. Also, the touch sensorpanel 100 is positioned between the first substrate 281 and the organicmaterial layer 280.

Here, the first substrate 281 may be made of encapsulation glass. Thesecond substrate 283 may be made of TFT glass. Also, the first substrate281 and/or the second substrate 283 may be plastic substrates. Since thetouch sensing has been described above, the other configurations onlywill be briefly described.

The OLED panel is a self-light emitting display panel which uses aprinciple where, when current flows through a fluorescent orphosphorescent organic thin film and then electrons and electron holesare combined in the organic material layer, so that light is generated.The organic matter constituting the light emitting layer determines thecolor of the light.

Specifically, the OLED uses a principle in which when electricity flowsand an organic matter is applied on glass or plastic, the organic matteremits light. That is, the principle is that electron holes and electronsare injected into the anode and cathode of the organic matterrespectively and are recombined in the light emitting layer, so that ahigh energy exciton is generated and the exciton releases the energywhile falling down to a low energy state and then light with aparticular wavelength is generated. Here, the color of the light ischanged according to the organic matter of the light emitting layer.

The OLED includes a line-driven passive-matrix organic light-emittingdiode (PM-OLED) and an individual driven active-matrix organiclight-emitting diode (AM-OLED) in accordance with the operatingcharacteristics of a pixel constituting a pixel matrix. None of themrequire a backlight. Therefore, the OLED enables a very thin displaymodule to be implemented, has a constant contrast ratio according to anangle and obtains a good color reproductivity depending on atemperature. Also, it is very economical in that non-driven pixel doesnot consume power.

In terms of operation, the PM-OLED emits light only during a scanningtime at a high current, and the AM-OLED maintains a light emitting stateonly during a frame time at a low current. Therefore, the AM-OLED has aresolution higher than that of the PM-OLED and is advantageous fordriving a large area display panel and consumes low power. Also, a thinfilm transistor (TFT) is embedded in the AM-OLED, and thus, eachcomponent can be individually controlled, so that it is easy toimplement a delicate screen.

As shown in FIGS. 2d and 2e , basically, the OLED (particularly,AM-OLED) panel includes the polarizer layer 282, the first substrate281, the organic layer 280, and the second substrate 283. Here, thefirst substrate 281 may be made of encapsulation glass. The secondsubstrate 283 may be made of TFT glass. However, they are not limited tothis. The first substrate 281 and/or the second substrate 283 may beplastic substrates.

Also, the organic layer 280 may include a hole injection layer (HIL), ahole transport layer (HTL), an emission material layer (EML), anelectron transport layer (ETL), and an electron injection layer (EIL).

Briefly describing each of the layers, HIL injects electron holes and ismade of a material such as CuPc, etc. HTL functions to move the injectedelectron holes and mainly is made of a material having a good holemobility. Arylamine, TPD, and the like may be used as the HTL. The EILand ETL inject and transport electrons. The injected electrons andelectron holes are combined in the EML and emit light. The EMLrepresents the color of the emitted light and is composed of a hostdetermining the lifespan of the organic matter and an impurity (dopant)determining the color sense and efficiency. This just describes thebasic structure of the organic layer 280 include in the OLED panel. Thepresent invention is not limited to the layer structure or material,etc., of the organic layer 280.

The organic layer 280 is inserted between an anode (not shown) and acathode (not shown). When the TFT becomes an on-state, a driving currentis applied to the anode and the electron holes are injected, and theelectrons are injected to the cathode. Then, the electron holes andelectrons move to the organic layer 280 and emit the light.

Also, according to the embodiment, at least a portion of the touchsensor may be disposed within the display panel 200A and at least theremaining portion of the touch sensor may be disposed outside thedisplay panel 200A. For example, any one of the drive electrode TX andthe receiving electrode RX which constitute the touch sensor panel 100may be disposed outside the display panel 200A and the other may bedisposed within the display panel 200A. When the touch sensor isdisposed within the display panel 200A, an electrode for the operationof the touch sensor may be further added. In addition, variouscomponents and/or electrodes disposed within the display panel 200A canbe also used as the touch sensor for touch sensing.

Also, according to the embodiment, at least a portion of the touchsensor may be disposed between the first substrate 261 and 281 and thesecond substrate 262 and 283 and at least the remaining portion of thetouch sensor may be disposed on the first substrate 261 and 281. Forexample, any one of the drive electrode TX and the receiving electrodeRX which constitute the touch sensor panel 100 may be disposed on thefirst substrate 261 and 281 and the other may be disposed between thefirst substrate 261 and 281 and the second substrate 262 and 283. Here,likewise, when the touch sensor is disposed between the first substrate261 and 281 and the second substrate 262 and 283, an electrode for theoperation of the touch sensor may be further added. In addition, variouscomponents and/or electrodes disposed between the first substrate 261and 281 and the second substrate 262 and 283 can be also used as thetouch sensor for touch sensing.

The second substrate 262 and 283 may be comprised of various layersincluding a data line a gate line, TFT, a common electrode, and a pixelelectrode, etc. Specifically, when the display panel 200A is the LCDpanel, these electrical components may operate in such a manner as togenerate a controlled electric field and orient liquid crystals locatedin the liquid crystal layer 250. Any one of the data line, the gateline, the common electrode, and the pixel electrode included in thesecond substrate 262 and 283 may be configured to be used as the touchsensor.

The foregoing has described the touch input device 1000 including thetouch sensor panel 100 capable of detecting whether or not the touch hasoccurred and/or the touch position. The pressure sensor 440 according tothe embodiment of the present invention is applied to the aforementionedtouch input device 1000, so that it is possible to easily detect amagnitude of a touch pressure as well as whether or not the touch hasoccurred and/or the touch position. Hereinafter, described in detail isan example of a case of detecting the touch pressure by applying theelectrode sheet according to the embodiment of the present invention tothe touch input device 1000. According to the embodiment, the touchinput device to which the pressure detection module is applied may nothave the touch sensor panel 100.

FIG. 3a is an exemplary cross sectional views of the pressure sensorincluding a pressure electrode according to the embodiment of thepresent invention. For example, the pressure sensor 440 may include anelectrode layer 441 between a first insulation layer 470 and a secondinsulation layer 471. The electrode layer 441 may include a firstelectrode 450 and/or a second electrode 460. Here, the first insulationlayer 470 and the second insulation layer 471 may be made of aninsulating material like polyimide. The first electrode 450 and/or thesecond electrode 460 included in the electrode layer 441 may include amaterial like copper. In accordance with the manufacturing process ofthe pressure sensor 440, the electrode layer 441 and the secondinsulation layer 471 may be adhered to each other by means of anadhesive (not shown) like an optically clear adhesive (OCA). Also, thepressure electrodes 450 and 460 according to the embodiment may beformed by positioning a mask, which has a through-hole corresponding toa pressure electrode pattern, on the first insulation layer 470, andthen by spraying a conductive material.

FIG. 4a is a cross sectional view of the touch input device of a firstexample, to which the pressure sensor and the pressure detection moduleaccording to the embodiment of the present invention can be applied.

The cross sectional view of the touch input device 1000 shown in FIG. 4amay be a cross sectional view of a portion of the touch input device1000. As shown in FIG. 4a , the touch input device 1000 according to theembodiment of the present invention may include the display panel 200A,a backlight unit 200B disposed under the display panel 200A, and a coverlayer 500 disposed on the display panel 200A. In the touch input device1000 according to the embodiment, the pressure sensors 450 and 460 maybe formed on a cover 240. In this specification, the display panel 200Aand the backlight unit 200B are collectively referred to as a displaymodule 200. FIG. 4a shows that the pressure sensors 450 and 460 areattached on the cover 240. However, according to the embodiment, thepressure sensors 450 and 460 can be also attached to a configurationwhich is included in the touch input device 1000 and performs the sameor similar function as/to that of the cover 240.

The touch input device 1000 according to the embodiment of the presentinvention may include an electronic device including the touch screen,for example, a cell phone, a personal data assistant (PDA), a smartphone, a tablet personal computer, an MP3 player, a laptop computer,etc.

At least a portion of the touch sensor is included within the displaypanel 200A in the touch input device 1000 according to the embodiment.Also, according to the embodiment, the drive electrode and the receivingelectrode which are for sensing the touch may be included within thedisplay panel 200A.

FIG. 4a does not show separately the touch sensor panel 100. However, inthe touch input device 1000 according to the first example of thepresent invention, the lamination is made by an adhesive like theoptically clear adhesive (OCA) between the touch sensor panel 100 andthe display module 200 for detecting the touch position. As a result,the display color clarity, visibility and optical transmittance of thedisplay module 200, which can be recognized through the touch surface ofthe touch sensor panel 100, can be improved. Here, the cover layer 500may be disposed on the touch sensor panel 100.

The cover layer 500 according to the embodiment may be comprised of acover glass which protects the front side of the display panel 200A andforms the touch surface. As shown in FIG. 4a , the cover layer 500 maybe formed wider than the display panel 200A.

Since the display panel 200A such as the LCD panel according to theembodiment performs a function of only blocking or transmitting thelight without emitting light by itself, the backlight unit 200B may berequired. For example, the backlight unit 200B is disposed under thedisplay panel 200A, includes a light source and throws the light on thedisplay panel 200A, so that not only brightness and darkness but alsoinformation having a variety of colors is displayed on the screen. Sincethe display panel 200A is a passive device, it is not self-luminous.Therefore, the rear side of the display panel 200A requires a lightsource having a uniform luminance distribution.

The backlight unit 200B according to the embodiment may include anoptical layer 220 for illuminating the display panel 200A. The opticallayer 220 will be described in detail with reference to FIG. 4 b.

The backlight unit 200B according to the embodiment may include thecover 240. The cover 240 may be made of a metallic material. When apressure is applied from the outside through the cover layer 500 of thetouch input device 1000, the cover layer 500, the display module 200,etc., may be bent. Here, the bending causes a distance between thepressure sensor 450 and 460 and a reference potential layer locatedwithin the display module to be changed. The capacitance change causedby the distance change is detected through the pressure sensors 450 and460, so that the magnitude of the pressure can be detected. Here, apressure is applied to the cover layer 500 in order to precisely detectthe magnitude of the pressure, the position of the pressure sensors 450and 460 needs to be fixed without changing. Therefore, the cover 240 isable to perform a function of a support capable of fixing a pressuresensor without being relatively bent even by the application ofpressure. According to the embodiment, the cover 240 is manufacturedseparately from the backlight unit 200B, and may be assembled togetherwhen the display module is manufactured.

In the touch input device 1000 according to the embodiment, a first airgap 210 may be included between the display panel 200A and the backlightunit 200B. This intends to protect the display panel 200A and/or thebacklight unit 200B from an external impact. This first air gap 210 maybe included in the backlight unit 200B.

The optical layer 220 and the cover 240, which are included in thebacklight unit 200B, may be configured to be spaced apart from eachother. A second air gap 230 may be provided between the optical layer220 and the cover 240. The second air gap 230 may be required in orderto ensure that the pressure sensors 450 and 460 disposed on the cover240 does not contact with the optical layer 220, and in order to preventthat the optical layer 220 contacts with the pressure sensors 450 and460 and deteriorates the performance of the optical layer 220 eventhough an external pressure is applied to the cover layer 500 and theoptical layer 220, the display panel 200A, and the cover layer 500 arebent.

The touch input device 1000 according to the embodiment may furtherinclude supports 251 and 252 such that the display panel 200A, thebacklight unit 200B, and the cover layer 500 are coupled to maintain afixed shape. According to the embodiment, the cover 240 may beintegrally formed with the support 251 and 252. According to theembodiment, the support 251 and 252 may form a portion of the backlightunit 200B.

The structure and function of the display panel 200A and the backlightunit 200B is a publicly known art and will be briefly described below.The backlight unit 200B may include several optical parts.

FIG. 4b shows the optical layer 220 of the backlight unit 200B in thetouch input device according to the embodiment. FIG. 4b shows theoptical layer 220 when the LCD panel is used as the display panel 200A.

In FIG. 4b , the optical layer 220 of the backlight unit 200B mayinclude a reflective sheet 221, a light guide plate 222, a diffusersheet 223, and a prism sheet 224. Here, the backlight unit 200B mayinclude a light source (not shown) which is formed in the form of alinear light source or point light source and is disposed on the rearand/or side of the light guide plate 222.

The light guide plate 222 may generally convert lights from the lightsource (not shown) in the form of a linear light source or point lightsource into light from a light source in the form of a surface lightsource, and allow the light to proceed to the LCD panel 200A.

A part of the light emitted from the light guide plate 222 may beemitted to a side opposite to the LCD panel 200A and be lost. Thereflective sheet 221 may be positioned below the light guide plate 222so as to cause the lost light to be incident again on the light guideplate 222, and may be made of a material having a high reflectance.

The diffuser sheet 223 functions to diffuse the light incident from thelight guide plate 222. For example, light scattered by the pattern ofthe light guide plate 222 comes directly into the eyes of the user, andthus, the pattern of the light guide plate 222 may be shown as it is.Moreover, since such a pattern can be clearly sensed even after the LCDpanel 200A is mounted, the diffuser sheet 224 is able to perform afunction to offset the pattern of the light guide plate 222.

After the light passes through the diffuser sheet 223, the luminance ofthe light is rapidly reduced. Therefore, the prism sheet 224 may beincluded in order to improve the luminance of the light by focusing thelight again. The prism sheet 224 may include, for example, a horizontalprism sheet and a vertical prism sheet.

The backlight unit 200B according to the embodiment may include aconfiguration different from the above-described configuration inaccordance with the technical change and development and/or theembodiment. The backlight unit 200B may further include an additionalconfiguration as well as the foregoing configuration. Also, in order toprotect the optical configuration of the backlight unit 200B fromexternal impacts and contamination, etc., due to the introduction of thealien substance, the backlight unit 200B according to the embodiment mayfurther include, for example, a protection sheet on the prism sheet 224.The backlight unit 200B may also further include a lamp cover inaccordance with the embodiment so as to minimize the optical loss of thelight source. The backlight unit 200B may also further include a framewhich maintains a shape enabling the light guide plate 222, the diffusersheet 223, the prism sheet 224, a lamp (not shown), and the like, whichare main components of the backlight unit 200B, to be exactly combinedtogether in accordance with an allowed dimension. Also, the each of theconfigurations may be comprised of at least two separate parts.

According to the embodiment, an additional air gap may be positionedbetween the light guide plate 222 and the reflective sheet 221. As aresult, the lost light from the light guide plate 222 to the reflectivesheet 221 can be incident again on the light guide plate 222 by thereflective sheet 221. Here, between the light guide plate 222 and thereflective sheet 221, for the purpose of maintaining the additional airgap, the double-sided adhesive tape (DAT) may be included on the edgesof the light guide plate 222 and the reflective sheet 221.

As described above, the backlight unit 200B and the display moduleincluding the backlight unit 200B may be configured to include in itselfthe air gap such as the first air gap 210 and/or the second air gap 230.Also, the air gap may be included between a plurality of the layersincluded in the optical layer 220. Although the foregoing has describedthat the LCD panel 200A is used, the air gap may be included within thestructure of another display panel.

FIG. 4c is a cross sectional view of the touch input device of a secondexample, to which the pressure sensor and pressure detection moduleaccording to the embodiment of the present invention can be applied.FIG. 4c shows a cross section of the touch input device 1000 thatfurther includes a substrate 300 as well as the display module 200. Inthe touch input device 1000 according to the embodiment, the substrate300, together with a second outermost cover 320 of the touch inputdevice 1000, functions as, for example, a housing which surrounds amounting space 310, etc., where the circuit board and/or battery foroperation of the touch input device 1000 are located. Here, the circuitboard for operation of the touch input device 1000 may be a main board.A central processing unit (CPU), an application processor (AP) or thelike may be mounted on the circuit board. Due to the substrate 300, thedisplay module 200 is separated from the circuit board and/or batteryfor operation of the touch input device 1000. Due to the substrate 300,electrical noise generated from the display module 200 can be blocked.According to the embodiment, the substrate 300 may be referred to as amid-frame in the touch input device 1000.

In the touch input device 1000, the cover layer 500 may be formed widerthan the display module 200, the substrate 300, and the mounting space310. As a result, the second cover 320 is formed in such a manner as tosurround the display module 200, the substrate 300, and the mountingspace 310 where the circuit board is located. Also, according to theembodiment, the pressure sensor 440 may be included between the displaymodule 200 and the substrate 300.

As with FIG. 4a , FIG. 4c does not show separately the touch sensorpanel 100. However, the touch input device 1000 according to theembodiment of the present invention can detect the touch positionthrough the touch sensor panel 100. Also, according to the embodiment,at least a portion of the touch sensor may be included in the displaypanel 200A.

Here, the pressure sensor 440 may be attached to the substrate 300, maybe attached to the display module 200, or may be attached to the displaymodule 200 and the substrate 300.

As shown in FIGS. 4a and 4c , since the pressure sensor 440 in the touchinput device 1000 is disposed within the display module 200 or isdisposed between the display module 200 and the substrate 300 and underthe display module 200, the electrodes 450 and 460 included in thepressure sensor 440 can be made of not only a transparent material butalso an opaque material.

Hereafter, in the touch input device 1000 according to the embodiment ofthe present invention, the principle and structure for detecting themagnitude of touch pressure by using the pressure sensor 440 will bedescribed in detail. In FIGS. 5a to 5e , for convenience of description,the electrodes 450 and 460 included in the pressure sensor 440 arereferred to as a pressure sensor.

FIGS. 5a and 5b show a relative distance between the reference potentiallayer and the pressure sensor of the first example, which are includedin the touch input device, and show a pressure is applied to the touchinput device. In the touch input device 1000 according to the embodimentof the present invention, the pressure sensors 450 and 460 may beattached on the cover 240 capable of constituting the backlight unit200B. In the touch input device 1000, the pressure sensors 450 and 460and the reference potential layer 600 may be spaced apart from eachother by a distance “d”.

In FIG. 5a , the reference potential layer 600 and the pressure sensor450 and 460 may be spaced apart from each other with a spacer layer (notshown) placed therebetween. Here, as described with reference to FIGS.4a and 4b , the spacer layer may be the first air gap 210, the secondair gap 230, and/or an additional air gap which are included in themanufacture of the display module 200 and/or the backlight unit 200B.When the display module 200 and/or the backlight unit 200A includes oneair gap, the one air gap is able to perform the function of the spacerlayer. When the display module 200 and/or the backlight unit 200Aincludes a plurality of air gaps, the plurality of air gaps are able tocollectively perform the function of the spacer layer.

In the touch input device 1000 according to the embodiment, the spacerlayer may be located between the reference potential layer 600 and thepressure sensors 450 and 460. As a result, when a pressure is applied tothe cover layer 500, the reference potential layer 600 is bent, so thata relative distance between the reference potential layer 600 and thepressure sensors 450 and 460 may be reduced. The spacer layer may beimplemented by the air gap.

According to the embodiment, the spacer layer 420 may be made of animpact absorbing material. Here, the impact absorbing material mayinclude sponge and a graphite layer. The spacer layer 420 may be filledwith a dielectric material in accordance with the embodiment. The spacerlayer 420 may be formed through a combination of the air gap, the impactabsorbing material, and the dielectric material.

In the touch input device 1000 according to the embodiment, the displaymodule 200 may be bent or pressed by the touch applying the pressure.The display module may be bent or pressed in such a manner as to showthe biggest transformation at the touch position. When the displaymodule is bent or pressed according to the embodiment, a positionshowing the biggest transformation may not match the touch position.However, the display module may be shown to be bent or pressed at leastat the touch position. For example, when the touch position approachesclose to the border, edge, etc., of the display module, the most bent orpressed position of the display module may not match the touch position.The border or edge of the display module may not be shown to be bentvery little depending on the touch.

Here, since the display module 200 in the touch input device 1000according to the embodiment of the present invention may be bent orpressed by the application of the pressure, the components (adouble-side adhesive tape, an adhesive tape 430, the supports 251 and252, etc.) which are disposed at the border in order to maintain the airgaps 210 and 310 and/or the spacer layer 420 may be made of an inelasticmaterial. That is, even though the components which are disposed at theborder in order to maintain the air gaps 210 and 310 and/or the spacerlayer 420 are not compressed or pressed, the touch pressure can bedetected by the bending, etc., of the display module 200.

When the cover layer 500, the display panel 200A, and/or the back lightunit 200B are bent or pressed at the time of touching the touch inputdevice 1000 according to the embodiment, the cover 240 positioned belowthe spacer layer, as shown in FIG. 4b , may be less bent or pressed dueto the spacer layer. While FIG. 5b shows that the cover 240 is not bentor pressed at all, this is just an example. The lowest portion of thecover 240 to which the pressure sensors 450 and 460 have been attachedmay be bent or pressed. However, the degree to which the lowest portionof the cover 240 is bent or pressed can be reduced by the spacer layer.

According to the embodiment, the spacer layer may be implemented in theform of the air gap. The spacer layer may be made of an impact absorbingmaterial in accordance with the embodiment. The spacer layer may befilled with a dielectric material in accordance with the embodiment.

FIG. 5b shows that a pressure is applied to the structure of FIG. 5a .For example, when the external pressure is applied to the cover layer500 shown in FIG. 4a , it can be seen that a relative distance betweenthe reference potential layer 600 and the pressure sensors 450 and 460is reduced from “d” to “d′”. Accordingly, in the touch input device 1000according to the embodiment, when the external pressure is applied, thereference potential layer 600 is configured to be more bent than thecover 240 to which the pressure sensors 450 and 460 have been attached,so that it is possible to detect the magnitude of touch pressure.

FIGS. 4a, 5a, and 5b show that a first electrode 450 and a secondelectrode 460 are included as the pressure sensors 450 and 460 fordetecting the pressure. Here, the mutual capacitance may be generatedbetween the first electrode 450 and the second electrode 460. Here, anyone of the first and the second electrodes 450 and 460 may be a driveelectrode and the other may be a receiving electrode. A driving signalis applied to the drive electrode, and a sensing signal may be obtainedthrough the receiving electrode. When voltage is applied, the mutualcapacitance may be generated between the first electrode 450 and thesecond electrode 460.

The reference potential layer 600 may have any potential which causesthe change of the mutual capacitance generated between the firstelectrode 450 and the second electrode 460. For instance, the referencepotential layer 600 may be a ground layer having a ground potential. Thereference potential layer 600 may be any ground layer which is includedin the display module. According to the embodiment, the referencepotential layer 600 may be a ground potential layer which is included initself during the manufacture of the touch input device 1000. Forexample, in the display panel 200A shown in FIGS. 2a to 2c , anelectrode (not shown) for blocking noise may be included between thefirst polarizer layer 271 and the first substrate 261. This electrodefor blocking the noise may be composed of ITO and may function as theground. Also, according to the embodiment, a plurality of the commonelectrodes included in the display panel 200A constitutes the referencepotential layer 600. Here, the potential of the common electrode may bea reference potential.

When a pressure is applied to the cover layer 500 by means of an object,at least a portion of the display panel 200A and/or the backlight unit200B is bent, so that a relative distance between the referencepotential layer 600 and the first and second electrodes 450 and 460 maybe reduced from “d” to “d′”. Here, the less the distance between thereference potential layer 600 and the first and second electrodes 450and 460 is, the less the value of the mutual capacitance between thefirst electrode 450 and the second electrode 460 may be. This is becausethe distance between the reference potential layer 600 and the first andsecond electrodes 450 and 460 is reduced from “d” to “d′”, so that afringing capacitance of the mutual capacitance is absorbed in thereference potential layer 600 as well as in the object. When anonconductive object touches, the change of the mutual capacitance issimply caused by only the change of the distance “d-d′” between thereference potential layer 600 and the electrodes 450 and 460.

The foregoing has described that the pressure sensor 440 includes thefirst electrode 450 and the second electrode 460 and the pressure isdetected by the change of the mutual capacitance between the firstelectrode 450 and the second electrode 460. The pressure sensor 440 maybe configured to include only any one of the first electrode 450 and thesecond electrode 460 (for example, the first electrode 450).

FIGS. 5c and 5d show a relative distance between a reference potentiallayer and a pressure sensor of a second example which are included inthe touch input device, and show that a pressure is applied to the touchinput device. Here, it is possible to detect the magnitude of touchpressure by detecting the self-capacitance between the first electrode450 and the reference potential layer 600. Here, the change of theself-capacitance between the first electrode 450 and the referencepotential layer 600 is detected by applying the driving signal to thefirst electrode 450 and by receiving the reception signal from the firstelectrode 450, so that the magnitude of the touch pressure is detected.

For example, the magnitude of the touch pressure can be detected by thechange of the capacitance between the first electrode 450 and thereference potential layer 600, which is caused by the distance changebetween the reference potential layer 600 and the first electrode 450.Since the distance “d” is reduced with the increase of the touchpressure, the capacitance between the reference potential layer 600 andthe first electrode 450 may be increased with the increase of the touchpressure.

FIGS. 4a and 5a to 5d show that the first electrode 450 and/or thesecond electrode 460 are relatively thick and they are directly attachedto the cover 240. However, this is just only for convenience ofdescription. In accordance with the embodiment, the first electrode 450and/or the second electrode 460 is the integral sheet-type pressuresensor 440 may be attached to the cover 240 and may have a relativelysmall thickness.

Although the foregoing has described that the pressure sensor 440 isattached to the cover 240 by referencing the touch input device 1000shown in FIG. 4a , the pressure sensor 440 may be disposed between thedisplay module 200 and the substrate 300 in the touch input device 1000shown in FIG. 4c . According to the embodiment, the pressure sensor 440may be disposed under the display module 200. In this case, thereference potential layer 600 may be any potential layer which isdisposed on the substrate 300 or within the display module 200. Also,according to the embodiment, the pressure sensor 440 may be attached tothe substrate 300. In this case, the reference potential layer 600 maybe any potential layer which is disposed on or within the display module200.

FIG. 5e shows the arrangement of pressure sensors of a third examplewhich is included in the touch input device. As shown in FIG. 5e , thefirst electrode 450 may be disposed on the substrate 300, and the secondelectrode 460 may be disposed under the display module 200. In thiscase, a separate reference potential layer may not be required. When apressure touch is performed on the touch input device 1000, a distancebetween the display module 200 and the substrate 300 may be changed, andthus, the mutual capacitance between the first electrode 450 and thesecond electrode 460 may be increased. Through the capacitance change,the magnitude of the touch pressure can be detected. Here, the firstelectrode 450 and the second electrode 460 may be included in the firstpressure sensor 440-1 and the second pressure sensor 440-2 respectivelyand attached to the touch input device 1000.

The foregoing has described that the reference potential layer 600 islocated apart from the components to which the pressure sensor 440 isattached in the touch input device 1000. It will be described in FIGS.6a to 6c that the component itself to which the pressure sensor 440 isattached in the touch input device 1000 functions as the referencepotential layer.

FIG. 6a is a cross sectional view showing a portion of the touch inputdevice to which the pressure sensor 440 has been attached according to afirst method. FIG. 6a shows that the pressure sensor 440 has beenattached on the substrate 300, the display module 200, or the cover 240.

As shown in FIG. 6b , the adhesive tape 430 having a predeterminedthickness may be formed along the border of the pressure sensor 440 soas to maintain the spacer layer 420. Though FIG. 6b shows that theadhesive tape 430 is formed along the entire border (for example, foursides of a quadrangle) of the pressure sensor 440, the adhesive tape 430may be formed only on at least a portion (for example, three sides of aquadrangle) of the border of the pressure sensor 440. Here, as shown inFIG. 6b , the adhesive tape 430 may not be formed on an area includingthe electrodes 450 and 460. As a result, when the pressure sensor 440 isattached to the substrate 300 or the display module 200 through theadhesive tape 430, the pressure electrodes 450 and 460 may be spacedapart from the substrate 300 or the display module 200 at apredetermined distance. According to the embodiment, the adhesive tape430 may be formed on the top surface of the substrate 300, the bottomsurface of the display module 200, the surface of the cover 240. Also,the adhesive tape 430 may be a double adhesive tape. FIG. 6b shows onlyone of the pressure electrodes 450 and 460.

FIG. 6c is a partial cross sectional view of the touch input device towhich the pressure sensor has been attached according to a secondmethod. In FIG. 6c , after the pressure sensor 440 is placed on thesubstrate 300, the display module 200, or the cover 240, the pressuresensor 440 may be fixed to the substrate 300, the display module 200, orthe cover 240 by means of the adhesive tape 430. For this, the adhesivetape 430 may come in contact with at least a portion of the pressuresensor 440 and at least a portion of the substrate 300, the displaymodule 200, or the cover 240. FIG. 6c shows that the adhesive tape 430continues from the top of the pressure sensor 440 to the exposed surfaceof the substrate 300, the display module 200, or the cover 240. Here,only a portion of the adhesive tape 430, which contacts with thepressure sensor 440, may have adhesive strength. Therefore, in FIG. 6c ,the top surface of the adhesive tape 430 may not have the adhesivestrength.

As shown in FIG. 6c , even if the pressure sensor 440 is fixed to thesubstrate 300, the display module 200, or the cover 240 by using theadhesive tape 430, a predetermined space, i.e., air gap may be createdbetween the pressure sensor 440 and the substrate 300, the displaymodule 200, or the cover 240. This is because the substrate 300, thedisplay module 200, or the cover 240 is not directly attached to thepressure sensor 440 by means of the adhesive and because the pressuresensor 440 includes the pressure electrodes 450 and 460 having apattern, so that the surface of the pressure sensor 440 may not be flat.The air gap of FIG. 6c may also function as the spacer layer 420 fordetecting the touch pressure.

FIGS. 7a to 7e show pressure electrode patterns included in the pressuresensor for pressure detection according to the embodiment of the presentinvention. FIGS. 7a to 7c show the patterns of the first electrode 450and the second electrode 460 included in the pressure sensor 440. Thepressure sensor 440 including the pressure electrode patterns shown inFIGS. 7a to 7c may be formed on the cover 240, the substrate 300 or onthe bottom surface of the display module 200. The capacitance betweenthe first electrode 450 and the second electrode 460 may be changeddepending on a distance between the reference potential layer 600 andthe electrode layer including both the first electrode 450 and thesecond electrode 460.

When the magnitude of the touch pressure is detected as the mutualcapacitance between the first electrode 450 and the second electrode 460is changed, it is necessary to form the patterns of the first electrode450 and the second electrode 460 so as to generate the range of thecapacitance required to improve the detection accuracy. With theincrease of a facing area or facing length of the first electrode 450and the second electrode 460, the size of the capacitance that isgenerated may become larger. Therefore, the pattern can be designed byadjusting the size of the facing area, facing length and facing shape ofthe first electrode 450 and the second electrode 460 in accordance withthe range of the necessary capacitance. FIGS. 7b to 7c show that thefirst electrode 450 and the second electrode 460 are formed in the samelayer, and show that the pressure electrode is formed such that thefacing length of the first electrode 450 and the second electrode 460becomes relatively longer. The patterns of the pressure electrodes 450and 460 shown in FIGS. 7b to 7c can be used to detect the pressure inthe principle described in FIGS. 5a and 5 c.

The electrode pattern shown in FIG. 7d can be used to detect thepressure in the principle described in FIGS. 5c and 5d . Here, thepressure electrode should not necessary have a comb teeth shape or atrident shape, which is required to improve the detection accuracy ofthe mutual capacitance change amount. The pressure electrode may have,as shown in FIG. 7d , a plate shape (e.g., quadrangular plate).

The electrode pattern shown in FIG. 7e can be used to detect thepressure in the principle described in FIG. 5e . Here, as shown in FIG.7e , the first electrode 450 and the second electrode 460 are disposedorthogonal to each other, so that the capacitance change amountdetection sensitivity can be enhanced.

FIGS. 8a and 8b show a relation between a magnitude of a touch pressureand a saturated area in the touch input device to which the pressuresensor 440 has been applied according to the embodiment of the presentinvention. Although FIGS. 8a and 8b show that the pressure sensor 440 isattached to the substrate 300, the following description can be appliedin the same manner to a case where the pressure sensor 440 is attachedto the display module 200 or the cover 240.

The touch pressure with a sufficient magnitude makes a state where thedistance between the pressure sensor 440 and the substrate 300 cannot bereduced any more at a predetermined position. Hereafter, the state isdesignated as a saturation state. For instance, as shown in FIG. 8a ,when the touch input device 1000 is pressed by a force “f”, the pressuresensor 440 contacts the substrate 300, and thus, the distance betweenthe pressure sensor 440 and the substrate 300 cannot be reduced anymore. Here, as shown on the right of FIG. 8a , the contact area betweenthe pressure sensor 440 and the substrate 300 may be indicated by “a”.However, in this case, when the magnitude of the touch pressure becomeslarger, the contact area between the pressure sensor 440 and thesubstrate 300 in the saturation state where the distance between thepressure sensor 440 and the substrate 300 cannot be reduced any more maybecome greater. For example, as shown in FIG. 8b , when the touch inputdevice 1000 is pressed by a force “F” greater than the force “f”, thecontact area between the pressure sensor 440 and the substrate 300 maybecome greater. As shown on the right of FIG. 8a , the contact areabetween the pressure sensor 440 and the substrate 300 may be indicatedby “A”. As such, the greater the contact area, the more the mutualcapacitance between the first electrode 450 and the second electrode 460may be reduced. Hereafter, it will be described that the magnitude ofthe touch pressure is calculated by the change of the capacitanceaccording to the distance change. This may include that the magnitude ofthe touch pressure is calculated by the change of the saturation area inthe saturation state.

FIGS. 8a and 8b are described with reference to the example shown inFIG. 6a . It is apparent that the description with reference to FIGS. 8aand 8b can be applied in the same manner to the examples described withreference to FIGS. 4a, 4c, 5a to 5e, and 6c . More specifically, themagnitude of the touch pressure can be calculated by the change of thesaturation area in the saturation state where the distance between thepressure sensor 440 and either the ground layer or the referencepotential layer 600 cannot be reduced any more.

The top surface of the substrate 300 may also have the ground potentialin order to block the noise. FIG. 9 shows the cross sections of thepressure sensor according to the embodiment of the present invention.Referring to (a) of FIG. 9, a cross section when the pressure sensor 440including the pressure electrodes 450 and 460 is attached to thesubstrate 300 or the display module 200 is shown. Here, in the pressuresensor 440, since the pressure electrodes 450 and 460 are disposedbetween the first insulation layer 470 and the second insulation layer471, a short-circuit can be prevented from occurring between thepressure electrodes 450 and 460 and either the substrate 300 or thedisplay module 200. Also, depending on the kind and/or implementationmethod of the touch input device 1000, the substrate 300 or the displaymodule 200 on which the pressure electrodes 450 and 460 are attached maynot have the ground potential or may have a weak ground potential. Inthis case, the touch input device 1000 according to the embodiment ofthe present may further include a ground electrode (not shown) betweenthe first insulation layer 470 and either the substrate 300 or thedisplay module 200. According to the embodiment, another insulationlayer (not shown) may be included between the ground electrode andeither the substrate 300 or the display module 200. Here, the groundelectrode (not shown) is able to prevent the size of the capacitancegenerated between the first electrode 450 and the second electrode 460,which are pressure electrodes, from increasing excessively.

Cross sections of a portion of the pressure sensor attached to the touchinput device in accordance with the embodiment of the present inventionare shown in (a) to (d) of FIG. 9.

For example, when the first electrode 450 and the second electrode 460included in the pressures sensor 440 are formed in the same layer, thepressure sensor 440 may be configured as shown in (a) of FIG. 9. Here,each of the first electrode 450 and the second electrode 460 shown in(a) of FIG. 9 may be, as shown in FIG. 13a , composed of a plurality oflozenge-shaped electrodes. Here, the plurality of the first electrodes450 are connected to each other in a first axial direction, and theplurality of the second electrodes 460 are connected to each other in asecond axial direction orthogonal to the first axial direction. Thelozenge-shaped electrodes of at least one of the first and the secondelectrodes 450 and 460 are connected to each other through a bridge, sothat the first electrode 450 and the second electrode 460 may beinsulated from each other. Also, the first electrode 450 and the secondelectrode 460 shown in (a) of FIG. 9 may be composed of an electrodehaving a form shown in FIG. 13 b.

In the pressure sensor 440, it can be considered that the firstelectrode 450 and the second electrode 460 are formed in differentlayers in accordance with the embodiment and form the electrode layer. Across section when the first electrode 450 and the second electrode 460are formed in different layers is shown in (b) of FIG. 9. As shown in(b) of FIG. 9, the first electrode 450 may be formed on the firstinsulation layer 470, and the second electrode 460 may be formed on thesecond insulation layer 471 positioned on the first electrode 450.According to the embodiment, the second electrode 460 may be coveredwith a third insulation layer 472. In other words, the pressure sensor440 may include the first to the third insulation layers 470 to 472, thefirst electrode 450, and the second electrode 460. Here, since the firstelectrode 450 and the second electrode 460 are disposed in differentlayers, they can be implemented so as to overlap each other. Forexample, the first electrode 450 and the second electrode 460 may be, asshown in FIG. 13c , formed similarly to the pattern of the driveelectrode TX and receiving electrode RX which are arranged in the formof M×N array. Here, M and N may be natural numbers greater than 1. Also,as shown in FIG. 13a , the lozenge-shaped first and the secondelectrodes 450 and 460 may be disposed in different layers respectively.

A cross section when the pressure sensor 440 is formed to include onlythe first electrode 450 is shown in (c) of FIG. 9. As shown in (c) ofFIG. 9, the pressure sensor 440 including the first electrode 450 may bedisposed on the substrate 300 or on the display module 200. For example,the first electrode 450 may be disposed as shown in FIG. 12 d.

A cross section when the first pressure sensor 440-1 including the firstelectrode 450 is attached to the substrate 300 and the second pressuresensor 440-2 including the second electrode 460 is attached to thedisplay module 200 is shown in (d) of FIG. 9. As shown in (d) of FIG. 9,the first pressure sensor 440-1 including the first electrode 450 may bedisposed on the substrate 300. Also, the second pressure sensor 440-2including the second electrode 460 may be disposed on the bottom surfaceof the display module 200.

As with the description related to (a) of FIG. 9, when substrate 300,the display module 200, or the cover 240 on which the pressure sensors450 and 460 are attached may not have the ground potential or may have aweak ground potential, the pressure sensor 440 may further include, asshown in (a) to (d) of FIG. 9, a ground electrode (not shown) under thefirst insulation layers 470, 470-1, and 470-2 disposed to contact thesubstrate 300, the display module 200, or the cover 240. Here, thepressure sensor 440 may further include an additional insulation layer(not shown) which is opposite to the first insulation layers 470, 470-1,and 470-2 such that the ground electrode (not shown) is located betweenthe additional insulation layer and the first insulation layers 470,470-1, and 470-2.

The foregoing has described the case where the touch pressure is appliedto the top surface of the touch input device 1000. However, even whenthe touch pressure is applied to the bottom surface of the touch inputdevice 1000, the pressure sensor 440 is able to detect the touchpressure in the same manner.

As shown in FIGS. 4 to 9, in the case where the pressure sensor 440according to the embodiment of the present invention is attached to thetouch input device, when a pressure is applied to the touch input deviceby the object 500, the display module 200 or the substrate 300 is bentor pressed, so that the magnitude of the touch pressure can becalculated. Here, for the purpose of describing the change of thedistance between the reference potential layer 600 and the pressuresensor 440, FIGS. 4 to 9 show that the display module 200, the substrate300, or only a portion of the display module 200 to which the pressureis directly applied by the object 500 is bent or pressed. However, themember to which the pressure is not directly applied by the object 500is also actually bent or pressed. However, since how much the member towhich the pressure is directly applied is bent or pressed is more thanhow much the member to which the pressure is not directly applied isbent or pressed, the descriptions of FIGS. 4 to 9 are possible. As such,when the pressure is applied to the touch input device, the pressuresensor 440 attached to the touch input device may be also bent orpressed. Here, when the pressure applied to the touch input device isreleased, the display module 200 or the substrate 300 is restored to itsoriginal state, and thus, the pressure sensor 440 attached to the touchinput device should also maintain its original shape. Also, when theoriginal shape of the pressure sensor 440 is difficult to maintain,there may be difficulties in the process of attaching the pressuresensor 440 to the touch input device. Therefore, it is recommended thatthe pressure sensor 440 should have a rigidity to maintain its originalshape.

When the pressure electrodes 450 and 460 included in the pressure sensor440 are made of soft conductive metal such as Al, Ag, and Cu, thepressure electrodes 450 and 460 have a low rigidity and a thickness ofonly several micrometers. Therefore, the original shape of the pressuresensor 440 is difficult to maintain only by the pressure electrodes 450and 460. Accordingly, it is recommended that the first insulation layer470 or the second insulation layer 471 which is disposed on or under thepressure electrodes 450 and 460 has a rigidity enough to maintain theoriginal shape of the pressure sensor 440.

Specifically, as shown in FIG. 3b , the pressure sensor 440 may includethe electrode layer and support layers 470 b and 471 b. Here, theelectrode layer may be composed of the pressure electrodes 450 and 460including the first electrode 450 and the second electrode 460. In thiscase, the pressure sensor 440 may be used to detect the change of thecapacitance between the first electrode 450 and the second electrode460, which is changed according to a relative distance change betweenthe electrode layer and the reference potential layer 600 which isdisposed apart from the pressure sensor 440. Also, the electrode layermay be composed of the pressure electrodes 450 and 460 including onlyone electrode. In this case, the pressure sensor 440 may be used todetect the capacitance change between the electrode layer and thereference potential layer 600, which is changed according to therelative distance change between the electrode layer and the referencepotential layer 600 which is disposed apart from the pressure sensor440.

Here, when the reference potential layer 600 which is disposed apartfrom the pressure sensor 440 does not have a uniform reference potentialaccording to each input position, or when the distance change betweenthe reference potential layer and the electrode layer is not uniform forthe pressure having the same magnitude in accordance with the inputposition, for example, when the surface of the reference potential layer600 which is disposed apart from the pressure sensor 440 is not uniform,it may be difficult to use the capacitance change amount between theelectrode layer and the reference potential layer 600 which is disposedapart from the pressure sensor 440. As shown in FIG. 3h , the pressuresensor 440 according to the embodiment of the present invention mayinclude a first electrode layer including the first electrode 450 andinclude a second electrode layer which includes the second electrode 460and is disposed apart from the first electrode layer. In this case, thepressure sensor 440 may be used to detect the capacitance change betweenthe first electrode layer and the second electrode layer, which ischanged according to a relative distance change between the firstelectrode layer and the second electrode layer. Here, any one of thefirst electrode layer and the second electrode layer may be thereference potential layer. As such, the capacitance change between theelectrode layers is detected, which is changed according to the distancechange between the electrode layers located within the pressure sensor440, so that it is possible to detect a uniform capacitance change evenwhen, as described above, the uniform capacitance change cannot bedetected from the reference potential layer located outside the pressuresensor 440. Here, an elastic layer 480 which has a restoring force andabsorbs the impact may be further included between the first electrodelayer and the second electrode layer in order to provide uniformity ofthe distance change between the first electrode layer and the secondelectrode layer. Also, as shown in (d) of FIG. 9, the pressure sensor440 may include the first pressure sensor including the first electrodelayer and a first support layer and the second pressure sensor includingthe second electrode layer and a second support layer. In this case, thepressure sensor 440 may be used to detect the capacitance change betweenthe first electrode layer and the second electrode layer, which ischanged according to the relative distance change between the firstelectrode layer and the second electrode layer.

The support layers 470 b and 471 b may be made of a material, forexample, a resin material, highly rigid metal, paper, or the like, whichhas a rigidity capable of maintaining the shape of the pressure sensor440 even when the distance change occurs between the pressure sensor 440and the reference potential layer 600.

The pressure sensor 440 may further include the first insulation layer470 and the second insulation layer 471. Here, the electrode layer maybe located between the first insulation layer 470 and the secondinsulation layer 471, and the support layers 470 b and 471 b may beincluded in at least any one of the first insulation layer 470 and thesecond insulation layer 471.

The first insulation layer 470 or the second insulation layer 471 mayfurther include electrode covering layers 470 a and 471 a. The electrodecovering layers 470 a and 471 a may function to insulate the electrodelayer and may function to protect the electrode layer, for example, toprevent the electrode from being oxidized, scraped, cracked, or thelike. Also, the electrode covering layers 470 a and 471 a are formed ofor coated with a material with a color, thereby preventing the electrodesheet 440 from being degraded due to exposure to the sun during thedistribution of the electrode sheet 440. Here, the electrode coveringlayers 470 a and 471 a may be adhered to the electrode layer or to thesupport layers 470 b and 471 b by means of an adhesive or may be printedor coated on the support layers 470 b and 471 b. The electrode coveringlayers 470 a and 471 a may be also made of a highly rigid resinmaterial. However, since the thickness of the electrode covering layeris only several micrometers, it is difficult to maintain the originalshape of the pressure sensor 440 of about 100 μm.

Also, as shown in FIGS. 3e and 3f , the pressure sensor 440 according tothe embodiment of the present invention may further include the adhesivelayer 430 and a protective layer 435 outside either the first insulationlayer 470 or the second insulation layer 471. Though it has beendescribed in FIGS. 4 to 9 that the adhesive layer 430 is formedseparately from the pressure sensor 440, the adhesive layer 430 may bemanufactured as one component included in the pressure sensor 440. Theprotective layer 435 functions to protect the adhesive layer 430 beforethe pressure sensor 440 is attached to the touch input device. When thepressure sensor 440 is attached to the touch input device, theprotective layer 435 is removed and the pressure sensor 440 can beattached to the touch input device by using the adhesive layer 430.

As shown in FIG. 3c , the electrode covering layers 470 a and 471 a maynot be formed on the side where the support layers 470 b and 471 b areformed. The support layers 470 b and 471 b made of a resin material,paper, or the like are able to insulate and protect the electrode layer.In this case, likewise, the support layers 470 b and 471 b may be formedof or coated with a material with a color.

As shown in FIG. 3d , any one of the first insulation layer 470 and thesecond insulation layer 471 may have a thickness less than that of theother. Specifically, since the capacitance (C) is inversely proportionalto the distance “d” between the electrode layer and the referencepotential layer 600, FIG. 3i shows that, for the same distance change,the smaller the distance between the electrode layer and the referencepotential layer 600 is, the greater the capacitance change amountbecomes, and then it becomes easier to precisely detect the pressure.Therefore, the pressure sensor 440 is attached to the touch input deviceincluding the cover 240, the substrate 300 and/or the display module200, and the thickness of one of the first and second insulation layers470 and 471, which is closer to the reference potential layer 600 thanthe other, may be less than that of the other.

Preferably, only one of the first and second insulation layers 470 and471 may include the support layers 470 b and 471 b. Specifically, in thestate where the pressure sensor 440 is attached to the touch inputdevice, only one of the first and second insulation layers 470 and 471,which is farther from the reference potential layer 600 than the other,may include the support layers 470 b and 471 b.

Likewise, as shown in (d) of FIG. 9, when the first pressure sensor440-1 is attached to the substrate 300 and the second pressure sensor440-2 is attached to the display module 200, the thickness of the secondinsulation layer 471-1 which is closer to the second electrode 460 outof the first and the second insulation layers 470-1 and 471-1 may beless than the thickness of the first insulation layer 470-1, thethickness of the fourth insulation layer 471-2 which is closer to thefirst electrode 450 out of the third and the fourth insulation layers470-2 and 471-2 may be less than the thickness of the third insulationlayer 470-2. Preferably, only the first and the third insulation layers470-1 and 470-2 may include the support layer 470 b.

As shown in FIG. 3h , even when the pressure sensor 440 includes thefirst electrode layer including the first electrode 450 and the secondelectrode layer which includes the second electrode 460 and is disposedapart from the first electrode layer, the thickness of any one of thefirst insulation layer 470 and the second insulation layer 471 may beless than that of the other. Specifically, in a case where the pressuresensor 440 is attached to the display module 200 or the substrate 300,when a pressure is applied to the touch input device, a distance betweenthe pressure sensor 440 and the member to which the pressure sensor 440has been attached is not changed. However, a distance between thepressure sensor 440 and the member to which the pressure sensor 440 hasbeen not attached is changed. Here, the capacitance change according tothe distance change between the pressure sensor 440 and the referencepotential layer 600 located outside the pressure sensor 440 is notdesired. Thus, it is preferable to minimize such a capacitance change.Therefore, the pressure sensor 440 is attached to the touch input deviceincluding the substrate 300 and the display module 200 in such a manneras to be attached to any one of a side of the substrate 300, which isopposite to the display module 200 and a side of the display module 200,which is opposite to the substrate 300. In a state where the pressuresensor 440 is attached to the touch input device, the thickness of oneof the first and second insulation layers 470 and 471, which is closerto the side to which the pressure sensor 440 has been attached than theother, may be less than that of the other.

Preferably, only one of the first and second insulation layers 470 and471 may include the support layers 470 b and 471 b. Specifically, in thestate where the pressure sensor 440 is attached to the touch inputdevice, only one of the first and second insulation layers 470 and 471,which is farther from the side to which the pressure sensor 440 has beenattached than the other, may include the support layers 470 b and 471 b.

The pressure sensor 440 shown in FIG. 3e is attached to the cover 240,the substrate 300 or the display module 200 toward the side on which theadhesive layer 430 is formed. The pressure sensor 440 shown in FIG. 3eis used to detect the magnitude of the pressure according to thedistance change between the electrode layer and the reference potentiallayer 600 formed in or on the member to which the pressure sensor 440has not been attached. The pressure sensor 440 shown in FIG. 3f isattached to the cover 240, the substrate 300 or the display module 200toward the side on which the adhesive layer 430 is formed. The pressuresensor 440 shown in FIG. 3f is used to detect the magnitude of thepressure according to the distance change between the electrode layerand the reference potential layer 600 formed in or on the member towhich the pressure sensor 440 has been attached.

A space in which the pressure sensor 440 is disposed, for example, aninterval between the display module 200 and the substrate 300 depends onthe touch input device and is about 100 to 500 μm. The thicknesses ofthe pressure sensor 440 and the support layers 470 b and 471 b arelimited according to the interval. As shown in FIG. 3g , when thepressure sensor is attached to the display module 200 and a distancebetween the display module 200 and the substrate 300 is 500 μm, it isdesirable that the pressure sensor 440 has a thickness of 50 μm to 450μm. If the thickness of the pressure sensor 440 is less than 50 μm, thethickness of the support layers 470 b and 471 b having a relatively highrigidity also becomes smaller, so that the original shape of thepressure sensor 440 is difficult to maintain. If the thickness of thepressure sensor 440 is larger than 450 μm, an interval between thepressure sensor 440 and the substrate 300, i.e., the reference potentiallayer, is significantly reduced below 50 μm, so that it is difficult tomeasure the pressure with a wide range.

The pressure sensor 440 is disposed in the touch input device.Therefore, as with the touch input device, the pressure sensor 440 isrequired to meet a given reliability under a predetermined condition,for example, temperature, humidity, etc. In order to meet thereliability that the appearance and characteristics are less changedunder a harsh condition of 85 to −40° C., a humidity condition of 85%,etc., it is desirable that the support layers 470 b and 471 b are madeof a resin material. Specifically, the support layers 470 b and 471 bmay be formed of polyimide (PI) or polyethylene terephthalate (PET).Also, polyethylene terephthalate costs less than polyimide. The materialconstituting the support layers 470 b and 471 b may be determined interms of cost and reliability.

As described above, in order to detect the pressure through the touchinput device 1000 to which the pressure sensor 440 is applied accordingto the embodiment of the present invention, it is necessary to sense thecapacitance change occurring in the pressure electrodes 450 and 460.Therefore, it is necessary for the driving signal to be applied to thedrive electrode out of the first and second electrodes 450 and 460, andit is required to detect the touch pressure by the capacitance changeamount by obtaining the sensing signal from the receiving electrode.According to the embodiment, it is possible to additionally include apressure detection device in the form of a pressure sensing IC for theoperation of the pressure detection. The pressure detection module (notshown) according to the embodiment of the present invention may includenot only the pressure sensor 440 for pressure detection but also thepressure detection device.

In this case, the touch input device repeatedly has a configurationsimilar to the configuration of FIG. 1 including the drive unit 120, thesensing unit 110, and the controller 130, so that the area and volume ofthe touch input device 1000 increase.

According to the embodiment, the touch detection device 1000 may applythe driving signal for pressure detection to the pressure sensor 440 byusing the touch detection device for the operation of the touch sensorpanel 100, and may detect the touch pressure by receiving the sensingsignal from the pressure sensor 440. Hereafter, the followingdescription will be provided by assuming that the first electrode 450 isthe drive electrode and the second electrode 460 is the receivingelectrode.

For this, in the touch input device 1000 to which the pressure sensor440 is applied according to the embodiment of the present invention, thedriving signal may be applied to the first electrode 450 from the driveunit 120, and the second electrode 460 may transmit the sensing signalto the sensing unit 110. The controller 130 may perform the scanning ofthe touch sensor panel 100, and simultaneously perform the scanning ofthe touch pressure detection, or the controller 130 performs thetime-sharing, and then may generate a control signal such that thescanning of the touch sensor panel 100 is performed in a first timeinterval and the scanning of the pressure detection is performed in asecond time interval different from the first time interval.

Therefore, in the embodiment of the present invention, the firstelectrode 450 and the second electrode 460 should be electricallyconnected to the drive unit 120 and/or the sensing unit 110. Here, it iscommon that the touch detection device for the touch sensor panel 100corresponds to the touch sensing IC 150 and is formed on one end of thetouch sensor panel 100 or on the same plane with the touch sensor panel100. The pressure electrode 450 and 460 included in the pressure sensor440 may be electrically connected to the touch detection device of thetouch sensor panel 100 by any method. For example, the pressureelectrode 450 and 460 may be connected to the touch detection devicethrough a connector by using the second PCB 210 included in the displaymodule 200. For example, conductive traces 461 which electrically extendfrom the first electrode 450 and the second electrode 460 respectivelymay be electrically connected to the touch sensing IC 150 through thesecond PCB 210, etc.

FIGS. 10a to 10b show that the pressure sensor 440 including thepressure electrodes 450 and 460 is attached to the bottom surface of thedisplay module 200. FIGS. 10a and 10b show the second PCB 210 on which acircuit for the operation of the display panel has been mounted isdisposed on a portion of the bottom surface of the display module 200.

FIG. 10a shows that the pressure sensor 440 is attached to the bottomsurface of the display module 200 such that the first electrode 450 andthe second electrode 460 are connected to one end of the second PCB 210of the display module 200. Here, the first electrode 450 and the secondelectrode 460 may be connected to the one end of the second PCB 210 byusing a double conductive tape. Specifically, since the thickness of thepressure sensor 440 and an interval between the substrate 300 and thedisplay module 200 where the pressure sensor 440 is disposed are verysmall, the thickness can be effectively reduced by connecting both thefirst electrode 450 and the second electrode 460 to the one end of thesecond PCB 210 by using the double conductive tape rather than by usinga separate connector. A conductive pattern may be printed on the secondPCB 210 in such a manner as to electrically connect the pressureelectrodes 450 and 460 to a necessary component like the touch sensingIC 150, etc. The detailed description of this will be provided withreference to FIGS. 11a to 11c . An attachment method of the pressuresensor 440 including the pressure electrodes 450 and 460 shown in FIG.10a can be applied in the same manner to the substrate 300 and the cover240.

FIG. 10b shows that the pressure sensor 440 including the firstelectrode 450 and the second electrode 460 is not separatelymanufactured but is integrally formed on the second PCB 210 of thedisplay module 200. For example, when the second PCB 210 of the displaymodule 200 is manufactured, a certain area is separated from the secondPCB, and then not only the circuit for the operation of the displaypanel but also the pattern corresponding to the first electrode 450 andthe second electrode 460 can be printed on the area. A conductivepattern may be printed on the second PCB 210 in such a manner as toelectrically connect the first electrode 450 and the second electrode460 to a necessary component like the touch sensing IC 150, etc.

FIGS. 11a to 11c show a method for connecting the pressure electrodes450 and 460 included in the pressure sensor 440 to the touch sensing IC150. In FIGS. 11a to 11c , the touch sensor panel 100 is includedoutside the display module 200. FIGS. 12a to 12c show that the touchdetection device of the touch sensor panel 100 is integrated in thetouch sensing IC 150 mounted on the first PCB 160 for the touch sensorpanel 100.

FIG. 11a shows that the pressure electrodes 450 and 460 included in thepressure sensor 440 attached to the display module 200 are connected tothe touch sensing IC 150 through a first connector 121. As shown in FIG.11a , in a mobile communication device such as a smart phone, the touchsensing IC 150 is connected to the second PCB 210 for the display module200 through the first connector 121. The second PCB 210 may beelectrically connected to the main board through a second connector 224.Therefore, through the first connector 121 and the second connector 224,the touch sensing IC 150 may transmit and receive a signal to and fromthe CPU or AP for the operation of the touch input device 1000.

Here, while FIG. 11a shows that the pressure sensor 440 is attached tothe display module 200 by the method shown in FIG. 10b , the firstelectrode 450 can be attached to the display module 200 by the methodshown in FIG. 10a . A conductive pattern may be printed on the secondPCB 210 in such a manner as to electrically connect the first electrode450 and the second electrode 460 to the touch sensing IC 150 through thefirst connector 121.

FIG. 11b shows that the pressure electrodes 450 and 460 included in thepressure sensor 440 attached to the display module 200 are connected tothe touch sensing IC 150 through a third connector 473. In FIG. 11b ,the pressure electrodes 450 and 460 may be connected to the main boardfor the operation of the touch input device 1000 through the thirdconnector 473, and in the future, may be connected to the touch sensingIC 150 through the second connector 224 and the first connector 121.Here, the pressure electrodes 450 and 460 may be printed on theadditional PCB separated from the second PCB 210. Otherwise, accordingto the embodiment, the pressure electrodes 450 and 460 may be attachedto the touch input device 1000 in the form of the pressure sensor 440shown in FIGS. 3a to 3h and may be connected to the main board throughthe connector 473 by extending the conductive trace, etc., from thepressure electrodes 450 and 460.

FIG. 11c shows that the pressure electrodes 450 and 460 are directlyconnected to the touch sensing IC 150 through a fourth connector 474. InFIG. 11c , the pressure electrodes 450 and 460 may be connected to thefirst PCB 160 through the fourth connector 474. A conductive pattern maybe printed on the first PCB 160 in such a manner as to electricallyconnect the fourth connector 474 to the touch sensing IC 150. As aresult, the pressure electrodes 450 and 460 may be connected to thetouch sensing IC 150 through the fourth connector 474. Here, thepressure electrodes 450 and 460 may be printed on the additional PCBseparated from the second PCB 210. The second PCB 210 may be insulatedfrom the additional PCB so as not to be short-circuited with each other.Also, according to the embodiment, the pressure electrodes 450 and 460may be attached to the touch input device 1000 in the form of thepressure sensor 440 shown in FIGS. 3a to 3h and may be connected to thefirst PCB 160 through the connector 474 by extending the conductivetrace, etc., from the pressure electrodes 450 and 460.

The connection method of FIGS. 11b and 11c can be applied to the casewhere the pressure sensor 440 including the pressure electrode 450 and460 is formed on the substrate 300 or on the cover 240 as well as on thebottom surface of the display module 200.

FIGS. 11a to 11c have been described by assuming that a chip on board(COB) structure in which the touch sensing IC 150 is formed on the firstPCB 160. However, this is just an example. The present invention can beapplied to the chip on board (COB) structure in which the touch sensingIC 150 is mounted on the main board within the mounting space 310 of thetouch input device 1000. It will be apparent to those skilled in the artfrom the descriptions of FIGS. 11a to 11c that the connection of thepressure electrodes 450 and 460 through the connector can be alsoapplied to another embodiment.

The foregoing has described the pressure electrodes 450 and 460, that isto say, has described that the first electrode 450 constitutes onechannel as the drive electrode and the second electrode 460 constitutesone channel as the receiving electrode. However, this is just anexample. According to the embodiment, the drive electrode and thereceiving electrode constitute a plurality of channels respectively.Here, a high-pressure detection accuracy of the touch can be obtained bythe plurality of channels constituted by the drive electrode and thereceiving electrode, and it is possible to detect multi pressure of amulti touch.

FIGS. 12a to 12d show that the pressure electrode of the presentinvention constitutes the plurality of channels. FIG. 12a shows thatfirst electrodes 450-1 and 450-2 and second electrodes 460-1 and 460-2constitute two channels respectively. FIG. 12a shows that all of thefirst electrodes 450-1 and 450-2 and the second electrodes 460-1 and460-2 which constitute the two channels are included in one pressuresensor 440. FIG. 12b shows that the first electrode 450 constitutes twochannels 450-1 and 450-2 and the second electrode 460 constitutes onechannel FIG. 12c shows the first electrode 450-1 to 450-5 constitutefive channels and the second electrode 460-1 and 460-5 constitute fivechannels. Even in this case, all of the electrodes constituting the fivechannels may be also included in one pressure sensor 440. FIG. 12d showsthat first electrodes 451 to 459 constitute nine channels and all of thefirst electrodes 451 to 459 are included in one pressure sensor 440.

As shown in FIGS. 12a to 12d and 13a to 13d , when the plurality ofchannels are formed, a conductive pattern which is electricallyconnected to the touch sensing IC 150 from each of the first electrode450 and/or the second electrode 460 may be formed.

Here, described is a case in which the plurality of channels shown inFIG. 12d are constituted. In this case, since a plurality of conductivepatterns 461 should be connected to the first connector 121 with alimited width, a width of the conductive pattern 461 and an intervalbetween the adjacent conductive patterns 461 should be small. Polyimideis more suitable for a fine process of forming the conductive pattern461 with such a small width and interval than polyethyleneterephthalate. Specifically, the support layers 470 b and 471 b of thepressure sensor 440, in which the conductive pattern 461 is formed, maybe made of polyimide. Also, a soldering process may be required toconnect the conductive pattern 461 to the first connector 121. For asoldering process which is performed at a temperature higher than 300°C., polyimide resistant to heat is more suitable than polyethyleneterephthalate relatively vulnerable to heat. Here, for the purpose ofreducing production costs, a portion of the support layers 470 b and 471b, in which the conductive pattern 461 is not formed, may be made ofpolyethylene terephthalate, and a portion of the support layers 470 band 471 b, in which the conductive pattern 461 is formed, may be made ofpolyimide.

FIGS. 12a to 12d and 13a to 13d show that the pressure electrodeconstitutes a single or a plurality of channels. The pressure electrodemay be comprised of a single or a plurality of channels by a variety ofmethods. While FIGS. 12a to 12d and 13a to 13d do not show that thepressure electrodes 450 and 460 are electrically connected to the touchsensing IC 150, the pressure electrodes 450 and 460 can be connected tothe touch sensing IC 150 by the method shown in FIGS. 11a to 11c andother methods.

In the foregoing description, the first connector 121 or the fourthconnector 474 may be a double conductive tape. Specifically, since thefirst connector 121 or the fourth connector 474 may be disposed at avery small interval, the thickness can be effectively reduced by usingthe double conductive tape rather than a separate connector. Also,according to the embodiment, the functions of the first connector 121and the fourth connector 474 can be implemented by a Flex-on-FlexBonding (FOF) method capable of achieving a small thickness.

Hereinafter, various methods in which the pressure sensor 440 detectsthe magnitude of the pressure of the touch on the basis of thecapacitance change amount detected from the channel.

Example of First Method

FIG. 20a is a flowchart for describing an example of a method fordetecting the magnitude of the touch pressure by using a plurality ofchannels in the touch input device according to the embodiment of thepresent invention.

When a pressure is applied to the touch surface (S10), the magnitude ofthe touch pressure is detected based on the sum of values obtained bymultiplying the change amounts of the capacitances detected in therespective channels and SNR improvement scaling factors assigned to therespective channels (S20). For example, the magnitude of the touchpressure can be calculated based on the sum of values obtained bymultiplying the change amounts of the capacitances detected in therespective fifteen first electrodes 450 in the pressure sensor 440 shownin FIG. 13d and the SNR improvement scaling factors assigned to therespective channels. As such, by using a sum of values obtained bymultiplying the pressure magnitudes detected from the respectivechannels (or the capacitance values corresponding thereto) and SNRimprovement scaling factors assigned to the respective channels, or byusing an average value of the sum, the accuracy of the pressuremagnitude detected by using the plurality of channels can be furtherimproved than the accuracy of the pressure magnitude detected by using asingle channel.

Example of Second Method

FIG. 14a is a view showing that a pressure is applied to a predeterminedposition in the pressure sensor shown in FIG. 13d . FIG. 14b is a crosssectional view showing a form in which the touch input device is bentwhen the touch pressure is applied to a touch surface corresponding to aposition “A” of FIG. 14a . FIG. 14c is a cross sectional view showing aform in which the touch input device is bent when the touch pressure isapplied to a touch surface corresponding to a position “C” of FIG. 14 a.

When the touch pressure is applied to the touch surface corresponding toa position “A” shown in FIG. 14a , that is, when the touch pressure isapplied to the central portion of the display module 200, the degree ofbending of the display module 200 may be relatively high as shown inFIG. 14b . On the other hand, when the touch pressure is applied to thetouch surface corresponding to a position “B” shown in FIG. 14a , thatis, when the touch pressure is applied to the edge of the display module200, the degree of bending of the display module 200 may be relativelysmall as shown in FIG. 14c . Specifically, as shown in FIGS. 14b and 14c, when the same touch pressure is applied, the distance d1 between thepressure electrode 450 and the position where the display module 200 ismost bent when the touch pressure is applied to the central portion ofthe display module 200 may be smaller than the distance d2 between thepressure electrode 450 and the position where the display module 200 ismost bent when the touch pressure is applied to the edge of the displaymodule 200. Therefore, even though the same touch pressure is applied,the capacitance change amounts detected in the respective channels aredifferent according to the position where the touch pressure is applied.Therefore, there is a requirement for a method capable of detecting amore accurate pressure value than the pressure value detected by usingthe sum or average of values obtained by multiplying the pressuremagnitudes detected from the respective channels or the capacitancescorresponding to the pressure magnitudes by the SNR improvement scalingfactors assigned to the respective channels.

FIG. 20b is a flowchart for describing another example of a method fordetecting the magnitude of the touch pressure by using a plurality ofchannels in the touch input device according to the embodiment of thepresent invention. FIG. 15 is a view showing a sensitivity correctionscaling factor assigned to each first electrode in the pressure sensorshown in FIG. 13 d.

When a pressure is applied to the touch surface (S100), the magnitude ofthe touch pressure is detected based on the sum of values obtained bymultiplying the change amounts of the capacitances detected in therespective channels, the sensitivity correction scaling factors assignedpreviously to the respective channels, and the SNR improvement scalingfactor assigned to the respective channels (S200). For example, as shownin FIG. 15, the sensitivity correction scaling factor of 1 is assignedto the first electrode 450 located at the central portion of the displaymodule 200, a scaling factor of 6 is assigned to the first electrodes450 adjacent to the first electrode 450 located at the central portion,and sensitivity correction scaling factors of 12 and 16 are respectivelyassigned to the first electrodes 450 located at the edge. As describedabove, when a smaller sensitivity correction scaling factor is assignedto the channel corresponding to the central portion of the displaymodule 200 and a larger sensitivity correction scaling factor isassigned to the channel corresponding to the edge of the display module200, the central portion of the display module 200 is, as shown in FIGS.14b and 14c , bent more than the edge of the display module 200 when thesame pressure is applied. Therefore, it is possible to offset that thechange amount of the capacitance detected at the central portion of thedisplay module 200 becomes greater than the change amount of thecapacitance detected at the edge of the display module 200. As a result,a more accurate pressure value can be calculated.

Example of Third Method

FIG. 16a is a graph for describing, when the pressure is applied to theposition shown in FIG. 14a , a relation between a volume change amountof the touch input device and the magnitude of the applied pressure.FIG. 16b is a cross sectional view showing the volume change amount ofthe touch input device shown in FIG. 14b . FIG. 16c is a cross sectionalview showing the volume change amount of the touch input device shown inFIG. 14 c.

When the same touch pressure is applied, a volume (hereinafter, referredto as volume change amount) at which the touch input device 1000 isdeformed when the touch pressure is applied to the central portion ofthe display module 200 may be greater than the volume change amount ofthe touch input device 1000 when the touch pressure is applied to theedge of the display module 200. In other words, when the same touchpressure is applied to the touch surface corresponding to the positions“A”, “B”, and “C” shown in FIG. 14a , as shown in FIGS. 16a to 16c , thevolume change amount of the touch input device 1000 when the touchpressure is applied to the position “A”, the central portion of thedisplay module 200, is greater than the volume change amount of thetouch input device 1000 when the touch pressure is applied the position“C” located at the edge relative to the position “A” of the displaymodule 200.

Here, when the touch pressure is applied to the same position, themagnitude of the applied pressure and the volume change amount of thetouch input device 1000 have a linear relationship. In other words, whenthe touch pressures having different magnitudes are applied to any oneof the positions “A”, “B”, and “C” shown in FIG. 14a , the volume changeamount of the touch input device 1000 is, as shown in FIG. 16a , changedin proportion to the magnitude of the applied pressure.

Therefore, the magnitude of the pressure can be detected by estimatingthe volume change amount of the touch input device 1000.

First, when a pressure having a predetermined magnitude is applied to apredetermined touch position of the display module 200, a referencevalue corresponding to the touch position is stored in a memory (notshown) on the basis of the capacitance detected from each channel. Inthis case, the reference value may be the volume change amount of thetouch input device 1000 calculated based on the capacitance detectedfrom each channel. Alternatively, the reference value may be anormalized pressure value having a linear relationship with the volumechange amount of the touch input device 1000, or may be a slope in thegraph shown in FIG. 16a . Such a method is repeatedly performed for eachtouch position, and the reference value for all positions of the entirearea of the display module 200 when a pressure having a predeterminedmagnitude is applied is stored in the memory. Here, since it isdifficult to generate the reference value for all positions of theentire area of the display module 200, the reference value may begenerated and stored only for a plurality of representative positionsspaced apart by a predetermined interval. For example, the volume changeamounts of 432 calculated based on each capacitance change amountdetected when a pressure of 800 g is applied to each of the touchpositions of 432 (18×24) spaced apart at regular intervals of thedisplay module 200 may be stored in the memory.

Next, a method for detecting the magnitude of the touch pressure byusing the reference value is shown.

FIG. 20c is a flowchart for describing further another example of amethod for detecting the magnitude of the touch pressure by using aplurality of channels in the touch input device according to theembodiment of the present invention. FIG. 17a is a partial perspectiveview for describing a form in which the touch input device is deformedwhen the pressure is applied to the touch input device. FIG. 17b is aview for describing the estimation of the volume change amount of thetouch input device when the pressure is applied to the touch inputdevice. FIG. 17c is a cross sectional view of FIG. 17 b.

When a pressure is applied to the touch surface (S1000), the touchposition is detected (S2000), and a distance change corresponding toeach channel is calculated from the change amount of the capacitancedetected in each channel (S3000).

The value of capacitance detected in each channel depends on theconfiguration of the pressure electrode or the configuration of thecircuit for sensing the touch pressure. However, when the touch pressureis applied, the value of capacitance can be represented by a function ofthe distance change “di” corresponding to each channel shown in FIG. 17c. Therefore, it is possible to calculate the distance change “di”corresponding to each channel by performing an inverse calculation onthe capacitance value detected from each channel Here, the distancechange “di” corresponding to each channel means a distance whichcorresponds to each channel and at which the surface of the touch inputdevice is deformed after the pressure is applied with respect to thetime before the pressure is applied.

FIG. 18a shows an equivalent circuit of a device for sensing a pressurecapacitance 11 between the first electrode 450 and the second electrode460 when, as shown in FIGS. 13a to 13c , the first electrode 450 iscomposed of the drive electrode TX and the second electrode 460 iscomposed of the receiving electrode RX, so that the magnitude of thetouch pressure is detected from the change of the mutual capacitancebetween the first electrode 450 and the second electrode 460. Here, arelational expression between the driving signal Vs and the outputsignal Vo can be expressed by the following equation (1).

$\begin{matrix}{v_{o} = {{- \frac{C_{P}}{C_{FB}}} \cdot v_{s}}} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

Here, among the capacitance between the first electrode 450 and thesecond electrode 460, the capacitance which is lost as a referencepotential layer is fringing capacitance. Here, the pressure capacitance11 can be expressed as follows.

C _(p) =C ₀ +C _(fringing) =C ₀ +αf(d)  Equation (2)

Here, Co is a fixed capacitance value generated between the firstelectrode 450 and the second electrode 460, and C_(fringing) is acapacitance value generated by fringing effect between the firstelectrode 450 and the second electrode 460. The equation (2) representsthe value of C_(fringing) by the distance “d” and a coefficient “α”. Thefixed capacitance means a capacitance generated by the first electrode450 and the second electrode 460 irrespective of the distance “d”between the reference potential layer and the electrode.

When a random pressure is applied to any position of the display module200, the distance change “di” corresponding to each channel can becalculated by performing an inverse calculation on the capacitancechange amounts detected in each of the channels, the equation (1), andthe equation (2).

FIG. 18b shows an equivalent circuit of a device for sensing thecapacitance 11 between the first electrode 450 and the referencepotential layer when, as shown in FIG. 13d , the driving signal isapplied to the first electrode 450 and the reception signal is detectedfrom the first electrode 450, so that the magnitude of the touchpressure is detected from the change of the self-capacitance of thefirst electrode 450.

When a first switch 21 is turned on, the pressure capacitor 11 ischarged to a power supply voltage VDD to which one end of the firstswitch 21 is connected. When a third switch 23 is turned on immediatelyafter the first switch 21 is turned off, the electric charges charged inthe pressure capacitor 11 are transferred to an amplifier 31 to obtainthe output signal Vo corresponding thereto. When a second switch 22 isturned on, all the electric charges remaining in the pressure capacitor11 are discharged. When the third switch 23 is turned on immediatelyafter the second switch 22 is turned off, the electric charges aretransferred to the pressure capacitor 11 through a feedback capacitor 32to obtain the output signal corresponding thereto. Here, the outputsignal Vo of the circuit shown in the figure can be expressed by thefollowing equation (3).

$\begin{matrix}{{v_{o} = {{- \frac{C_{P}}{C_{FB}}} \cdot V_{DD}}}{v_{o} = {{- \frac{ɛA}{C_{FB}}} \cdot \frac{1}{d} \cdot V_{DD}}}} & {{Equation}\mspace{14mu} (3)}\end{matrix}$

Here, ε is a dielectric constant ε₀ε_(r) of the material filled betweenthe first electrode 450 and the reference potential layer, and “A” isthe area of the first electrode 450.

When a random pressure is applied to any position of the display module200, the distance change “di” corresponding to each channel can becalculated by performing an inverse calculation on the capacitancechange amounts detected in each of the channels and the equation (3).

The volume change amount of the touch input device is estimated by usingthe calculated distance change “di” corresponding to each channel(S4000). Specifically, when the touch pressure is applied, the surfaceof the touch input device 1000 is deformed as shown in FIG. 17a , andthe volume change amount of the touch input device 1000 due to thedeformation of the surface of the touch input device 1000 can beestimated as the sum of the volume change amounts corresponding to therespective channels shown in FIGS. 17b and 17c . Here, when the areascorresponding to the respective channels are the same, for example, whenthe areas of the first electrodes 450 shown in FIG. 13d are the same,the sum of the volume change amounts corresponding to the respectivechannels may be a value obtained by multiplying the sum of the distancechanges “di” corresponding to the respective channels by by the area “A”of the first one electrode 450.

Here, when the touch pressure is applied to a predetermined position,the magnitude of the applied pressure and the volume change amount ofthe touch input device 1000 have, as shown in FIG. 16a , a linearrelationship. Therefore, the magnitude of the applied pressure iscalculated on the basis of the estimated volume change amount of thetouch input device 1000, the SNR improvement scaling factors assigned tothe respective channels, and the reference value which is stored in thememory and corresponds to the touch position (S5000).

For example, on the assumption that the SNR improvement scaling factorsassigned to the respective channels are all 1, when the estimated volumechange amount of the touch input device 1000 is 1000 and the volumechange amount stored in the memory as a reference value corresponding tothe touch position for a pressure of 800 g is 2000, the magnitude of theapplied pressure is 400 g.

Also, when the reference value corresponding to the input touch positionis not stored in the memory, the pressure value can be calculatedthrough various interpolations such as linear interpolation, bi-cubicinterpolation, etc., by using the reference value which is stored in thememory and corresponds to a touch position adjacent to the input touchposition.

FIG. 19a is a view for describing a case where a pressure is applied toa position of the pressure sensor shown in FIG. 14a , which correspondsto a position “D” of FIG. 19a . FIG. 19b is a graph for describing thecalculation of the pressure value when the pressure is applied to theposition “D” shown in FIG. 19 a.

For example, when reference values corresponding to the position “A” andthe position “B” shown in FIG. 19a are stored in the memory and when areference value corresponding to the position “D” which is a mid-pointbetween the position “A” and the position “B” is not stored in thememory, the reference value of the position “D” can be, as shown in FIG.19b , estimated by linearly interpolating the reference values of theposition “A” and the position “B”, that is to say, by taking anintermediate value between the reference value of the position “A” andthe reference value of the position “B”. The magnitude of the pressureapplied to the position “D” can be calculated by using the estimatedreference value of the position “D”.

As described above, by calculating the magnitude of the pressure on thebasis of the volume change amount by the touch pressure, it is possibleto detect a more accurate pressure magnitude. The accurate magnitude ofthe pressure can be detected even though the reference potential layeror the pressure sensor is deformed from its initial position.

Hereinafter, a method for calculating the SNR improvement scaling factorwill be described.

FIG. 21a is a graph showing an amplitude of a signal includinginformation on the capacitance detected in the channel corresponding tothe position “a” of FIG. 17c . FIG. 21b is a graph showing an amplitudeof a signal including information on the capacitance detected in thechannel corresponding to the position “b” of FIG. 17 c.

As shown in FIG. 17c , when a touch pressure is applied to the centralportion of the display module, the amplitude of the signal includinginformation on the capacitance detected in the channel corresponding tothe position “a” may be greater than the amplitude of the signalincluding information on the capacitance detected in the channelcorresponding to the position “b”. Here, the capacitance detected ineach channel may be changed by various factors such as the change in anelectric field or a magnetic field around the touch input device 1000,temperature variation, and the like, as well as the pressure applied tothe touch input device 1000. The capacitance change due to the factorsother than the pressure applied to the touch input device 1000corresponds to noise to be removed in the detection of the magnitude ofthe pressure. As shown in FIGS. 21a and 21b , the signal includinginformation on the capacitance detected in each channel is detected in aform in which a signal due to the applied pressure and a signal due tonoise are combined. Here, as shown in FIG. 21a , a proportion occupiedby the amplitude of the signal due to the pressure among the signalsdetected at the position “a” corresponding to the central portion of thedisplay module, that is to say, the position to which the pressure hasbeen applied, occupies is larger than a proportion occupied by theamplitude of the signal due to noise. On the other hand, as shown inFIG. 21b , a proportion occupied by the amplitude of the signal due tothe pressure among the signals detected at the position “b”corresponding to the edge of the display module, which is far from theposition to which the pressure has been applied, is relatively less thana proportion occupied by the amplitude of the signal due to noise. Here,since the amplitude of the signal due to noise is generally constantirrespective of the position to which the pressure has been applied, theamplitude of the signal due to noise detected in each channels isgenerally constant. However, since the amplitude of the signal due tothe pressure is different depending on the position to which thepressure has been applied, the amplitude of the signal due to thepressure detected in each channel is different depending on the positionto which the pressure has been applied.

Therefore, in the detection of the pressure magnitude, by excluding asignal which is detected in a channel where the amplitude of the signaldue to noise is relatively larger than the amplitude of the signal dueto the pressure, or by reducing how much the signal contributes to thedetection of the magnitude of the pressure, how much the amplitude ofthe signal due to noise is reduced is higher than how much the amplitudeof the signal due to the pressure is reduced. Therefore, overall SNR canbe improved. Specifically, overall SNR at the time of detecting thepressure can be improved by assigning an appropriate SNR improvementscaling factor to each channel.

Here, the position to which the pressure has been applied and theposition where the display module shows the largest deformation do notnecessarily match each other. However, generally, the display module ismore greatly deformed at the position to which the pressure has beenapplied than other positions. Therefore, the amplitude of the signalincluding information on the capacitance detected in the channelcorresponding to the position to which the pressure has been applied isgenerally greater than the amplitude of the signal including informationon the capacitance detected in the channel corresponding to the otherpositions.

Therefore, the SNR improvement scaling factor which is assigned to eachchannel can be calculated according to the amplitude of the signalincluding information on the capacitance detected at the position towhich the pressure has been applied, i.e., the touch position ordetected in each channel.

FIGS. 22a and 22b are views for describing the SNR improvement scalingfactor which is assigned to each channel when a pressure is applied to aposition “P”. FIG. 22c is a view showing capacitance change amountsdetected in the respective channels when the pressure is applied to theposition “P”.

First, a method for calculating the SNR improvement scaling factor onthe basis of the amplitude of the signal including information on thecapacitance detected in each channel will be described.

The SNR improvement scaling factor of 1 may be assigned to N number ofthe channels in which the signal with the largest amplitude is detectedamong the signals detected in the respective channels, and the SNRimprovement scaling factor of 0 may be assigned to the remainingchannels. In this case, the pressure is detected by using only somechannels in which the signal with a large amplitude is detected amongthe total channels, and SNR can be improved by excluding the channel inwhich the signal with a small amplitude in detecting the pressure. Here,N is a natural number equal to or greater than 1 and equal to or smallerthan the total number of the channels. Specifically, when a pressure isapplied to the position “P” of FIG. 22a and N is four, the SNRimprovement scaling factor of 1 is assigned to the channels CH2, CH4,CH5, and CH8 of FIG. 22c in which the four signals with the largestamplitude are detected, and the SNR improvement scaling factor of 0 isassigned to the remaining channels. Here, by applying the SNRimprovement scaling factor to the above-described example of the firstmethod, the magnitude of the pressure can be detected by using 310 thatis a sum of the capacitance change amounts detected in CH2, CH4, CH5,and CH8. Also, the SNR improvement scaling factor of 1 may be assignedto a channel in which a signal with an amplitude equal to or greaterthan a predetermined ratio of the amplitude of the signal with thelargest amplitude among the signals detected in the respective channelsis detected, and the SNR improvement scaling factor of 0 may be assignedto the remaining channels. In this case as well, the pressure isdetected by using only some channels in which the signal with a largeamplitude is detected among the total channels, and SNR can be improvedby excluding the channel in which the signal with a small amplitude indetecting the pressure. Specifically, when a pressure is applied to theposition “P” of FIG. 22a and the predetermined ratio is 50%, the SNRimprovement scaling factor of 1 is assigned to the channels CH4, CH5,and CH8 shown in FIG. 22c , in which a signal with an amplitude equal toor greater than 55 that is 50% of the amplitude of the signal outputfrom the channel CH5 in which the signal with the largest amplitude isdetected is detected. The SNR improvement scaling factor of 0 isassigned to the remaining channels. Here, by applying the SNRimprovement scaling factor to the above-described example of the firstmethod, the magnitude of the pressure can be detected by using 260 thatis a sum of the capacitance change amounts detected in CH4, CH5, andCH8.

Also, a method for calculating the SNR improvement scaling factor on thebasis of the touch position will be described.

The SNR improvement scaling factor of 1 may be assigned to N number ofthe channels which are the closest to the touch position, and the SNRimprovement scaling factor of 0 may be assigned to the remainingchannels. In this case, the amplitude of the signal detected in thechannel close to the touch position is generally greater than theamplitude of the signal detected in the channel relatively far from thetouch position. Therefore, the pressure is detected by using only somechannels in which the signal with a large amplitude is detected amongthe total channels, and SNR can be improved by excluding the channel inwhich the signal with a small amplitude in detecting the pressure. Here,N is a natural number equal to or greater than 1 and equal to or smallerthan the total number of the channels.

Specifically, when a pressure is applied to the position “P” of FIG. 22aand N is four, the SNR improvement scaling factor of 1 is assigned tothe channels CH4, CH5, CH7, and CH8 of FIG. 22c , which are the closestto the touch position, and the SNR improvement scaling factor of 0 isassigned to the remaining channels. Here, by applying the SNRimprovement scaling factor to the above-described example of the firstmethod, the magnitude of the pressure can be detected by using 305 thatis a sum of the capacitance change amounts detected in CH4, CH5, CH7,and CH8.

Also, the SNR improvement scaling factor of 1 is assigned to the channellocated within a predetermined distance from the touch position, and theSNR improvement scaling factor of 0 is assigned to the remainingchannels. In this case as well, the pressure is detected by using onlysome channels in which the signal with a large amplitude is detectedamong the total channels, and SNR can be improved by excluding thechannel in which the signal with a small amplitude in detecting thepressure. Specifically, when a pressure is applied to the position “P”of FIG. 22a and the predetermined distance is “r” shown in FIG. 22a ,the SNR improvement scaling factor of 1 is assigned to the channels CH1,CH2, CH4, CH5, CH6, CH7, and CH8 which are, as shown in FIG. 22c ,located within the distance “r”, and the SNR improvement scaling factorof 0 is assigned to the remaining channels. Here, by applying the SNRimprovement scaling factor to the above-described example of the firstmethod, the magnitude of the pressure can be detected by using 385 thatis a sum of the capacitance change amounts detected in CH1, CH2, CH4,CH5, CH6, CH7, and CH8.

Also, the SNR improvement scaling factor which is assigned to eachchannel can be calculated based on a distance between the touch positionand each channel. For example, the distance between the touch positionand each channel may be inversely proportional to the SNR improvementscaling factor which is assigned to each channel. Here, SNR can beimproved by reducing how much the signal with a small amplitude amongthe total channels contributes to the detection of the pressure.Specifically, when a pressure is applied to the position “P” of FIG. 22band a distance between the touch position and the channel j is “dj”, theSNR improvement scaling factor proportional to “1/dj” may be assigned tothe channel j. For example, when “dl” to “d15” shown in FIG. 22b havevalues of 15, 13.5, 13.3, 11.3, 9.3, 8.8, 8.5, 5.3, 4.5, 7.3, 3.3, 1,8.5, 5.3, and 4.5, “1/dj”s of 0.067, 0.074, 0.075, 0.088, 0.108, 0.114,0.118, 0.189, 0.122, 0.137, 0.303, 1, 0.118, 0.189, and 0.222 areassigned as the SNR improvement scaling factor to CH1 to CH15respectively. By applying the SNR improvement scaling factor to theabove-described example of the first method, the magnitude of thepressure can be detected by using a sum of values obtained bymultiplying the capacitance change amounts detected in the respectivechannels by the SNR improvement scaling factor.

The foregoing has described the example of applying the SNR improvementscaling factor to the above-described example of the first method.Additionally, it is possible to detect the magnitude of the pressure byapplying the SNR improvement scaling factor to the example of the secondmethod or the third method in the same manner.

Although the pressure sensor 440 having the type shown in FIG. 13d hasbeen described above, the embodiment of the present invention is notlimited to this. The embodiment of the present invention can be appliedto a pressure sensor including the pressure electrode having the typesshown in FIGS. 13a to 13 c.

When the pressure sensor 440 is configured to form a plurality ofchannels, multi pressure of a multi touch can be detected. This can beperformed, for example, by using the pressure magnitudes obtained fromthe channels of the pressure electrodes 450 and 460 disposed at aposition corresponding to each of the multiple touch positions obtainedfrom the touch sensor panel 100. Alternatively, when the pressure sensor440 is configured to form a plurality of channels, the touch positioncan be directly detected by the pressure sensor 440, and multi pressurecan be also detected by using the pressure magnitudes obtained from thechannels of the pressure electrodes 450 and 460 disposed at thecorresponding position.

Although embodiments of the present invention were described above,these are just examples and do not limit the present invention. Further,the present invention may be changed and modified in various ways,without departing from the essential features of the present invention,by those skilled in the art. For example, the components described indetail in the embodiments of the present invention may be modified.Further, differences due to the modification and application should beconstrued as being included in the scope and spirit of the presentinvention, which is described in the accompanying claims.

REFERENCE NUMERALS

1000: touch input device 100: touch sensor panel 120: drive unit 110:sensing unit 130: controller 200: display module 300: substrate 400:pressure detection module 420: spacer layer 440: pressure sensor 450,460: electrode 470: first insulation layer 471: second insulation layer470a, 471a: electrode covering layer 470b, 471b: support layer 430:adhesive layer 435: protective layer 480: elastic layer

1. A touch input device capable of detecting a pressure of a touch on atouch surface, the touch input device comprising: a display module; anda pressure sensor which is disposed at a position where a distancebetween the pressure sensor and a reference potential layer ischangeable according to the touch on the touch surface, wherein thedistance is changeable according to a pressure magnitude of the touch,wherein the pressure sensor outputs a signal comprising information on acapacitance which is changed according to the distance, wherein thepressure sensor comprises a plurality of electrodes to form a pluralityof channels, and wherein the pressure magnitude of the touch is detectedon the basis of a change amount of the capacitance detected in each ofthe channels and an SNR improvement scaling factor assigned to each ofthe channels.
 2. The touch input device of claim 1, wherein the SNRimprovement scaling factor is calculated based on an amplitude of thesignal or a position of the touch.
 3. The touch input device of claim 2,wherein the SNR improvement scaling factor of 1 is assigned to N numberof the channels in which the signal with a largest amplitude is detectedamong the signals detected in the respective channels, and the SNRimprovement scaling factor of 0 is assigned to the remaining channels.4. The touch input device of claim 2, wherein the SNR improvementscaling factor of 1 is assigned to a channel in which a signal with anamplitude equal to or greater than a predetermined ratio of theamplitude of the signal with a largest amplitude among the signalsdetected in the respective channels is detected, and the SNR improvementscaling factor of 0 is assigned to the remaining channels.
 5. (canceled)6. The touch input device of claim 2, wherein the SNR improvementscaling factor of 1 is assigned to N number of the channels which arethe closest to the touch position, and the SNR improvement scalingfactor of 0 is assigned to the remaining channels.
 7. The touch inputdevice of claim 2, wherein the SNR improvement scaling factor of 1 isassigned to the channel located within a predetermined distance from thetouch position, and the SNR improvement scaling factor of 0 is assignedto the remaining channels.
 8. The touch input device of claim 2, whereinthe SNR improvement scaling factor which is assigned to each of thechannels is calculated based on a distance between the touch positionand each of the channels, and wherein the distance between the touchposition and each of the channels is inversely proportional to the SNRimprovement scaling factor which is assigned to each of the channels. 9.(canceled)
 10. The touch input device of claim 1, wherein the magnitudeof the touch pressure is detected based on a sum of values obtained bymultiplying the change amounts of the capacitances detected in therespective channels and the SNR improvement scaling factors assigned tothe respective channels.
 11. The touch input device of claim 1, whereinthe pressure magnitude of the touch is detected based on a sum of valuesobtained by multiplying the change amount of the capacitance detected ineach of the channels, a sensitivity correction scaling factor assignedpreviously to each of the channels, and the SNR improvement scalingfactor assigned previously to each of the channels and wherein thesensitivity correction scaling factor assigned to the channelcorresponding to a central portion of the display module is smaller thanthe sensitivity correction scaling factor assigned to the channelcorresponding to an edge of the display module.
 12. (canceled)
 13. Thetouch input device of claim 1, wherein a volume change amount of thetouch input device is estimated based on the change amount of thecapacitance detected in each of the channels, wherein the pressuremagnitude of the touch is detected based on the estimated volume changeamount and the SNR improvement scaling factor assigned to each of thechannel, wherein the pressure magnitude of the touch is detected basedon the estimated volume change amount, the SNR improvement scalingfactor assigned to each of the channels, and a reference valuecorresponding to a previously stored predetermined touch position, andwherein the volume change amount of the touch input device is estimatedby calculating a distance change corresponding to each of the channelsfrom the change amount of the capacitance detected in each of thechannels. 14-15. (canceled)
 16. The touch input device of claim 1,further comprising a substrate under the display module, wherein thepressure sensor is attached to the substrate or the display module,wherein the reference potential layer is the substrate or the displaymodule, or the reference potential layer is disposed within the displaymodule. 17-20. (canceled)
 21. The touch input device of claim 1, whereinthe display module comprises: a display panel; and a backlight unitwhich is disposed under the display panel and comprises a reflectivesheet and a cover, wherein the pressure sensor is attached to the cover,between the reflective sheet and the cover, wherein the referencepotential layer is located within the display panel, and wherein thereference potential layer is a common electrodes within the displaypanel. 22-24. (canceled)
 25. A method for detecting a pressure magnitudeof a touch by using a plurality of channels in a touch input devicewhich comprises a display module and constitutes the plurality ofchannels for detecting the pressure, the method comprising detecting thepressure magnitude the touch on the basis of a change amount ofcapacitances detected in the respective channels and an SNR improvementscaling factor assigned to each of the channels.
 26. The method of claim25, wherein the detecting the pressure magnitude of the touch isdetecting the pressure magnitude of the touch on the basis of a sum ofvalues obtained by multiplying a change amount of a capacitance detectedin each of the channels, a sensitivity correction scaling factorassigned previously to each of the channels, and an SNR improvementscaling factor assigned previously to each of the channels, and whereinthe sensitivity correction scaling factor assigned to the channelcorresponding to a central portion of the display module is smaller thanthe sensitivity correction scaling factor assigned to the channelcorresponding to an edge of the display module.
 27. (canceled)
 28. Themethod of claim 25, wherein the detecting the pressure magnitude of thetouch is: estimating a volume change amount of the touch input device onthe basis of a change amount of a capacitance detected in each of thechannels; detecting the pressure magnitude of the touch on the basis ofthe estimated volume change amount and an SNR improvement scaling factorassigned to each of the channels; detecting the pressure magnitude ofthe touch on the basis of the estimated volume change amount, the SNRimprovement scaling factor assigned to each of the channels, and areference value corresponding to a previously stored predetermined touchposition, and estimating a volume change amount of the touch inputdevice is estimating the volume change amount of the touch input deviceby calculating a distance change corresponding to each of the channelsfrom the change amount of the capacitance detected in each of thechannels. 29-30. (canceled)
 31. The method of claim 25, wherein the SNRimprovement scaling factor is calculated based on an amplitude of asignal including information on the change amount of the capacitancedetected in each of the channels or a position of the touch.
 32. Themethod of claim 31, wherein the SNR improvement scaling factor of 1 isassigned to N number of the channels in which the signal with a largestamplitude is detected among the signals detected in the respectivechannels, and the SNR improvement scaling factor of 0 is assigned to theremaining channels.
 33. The method of claim 31, wherein the SNRimprovement scaling factor of 1 is assigned to a channel in which asignal with an amplitude equal to or greater than a predetermined ratioof the amplitude of the signal with a largest amplitude among thesignals detected in the respective channels is detected, and the SNRimprovement scaling factor of 0 is assigned to the remaining channels.34. (canceled)
 35. The method of claim 31, wherein the SNR improvementscaling factor of 1 is assigned to N number of the channels which arethe closest to the touch position, and the SNR improvement scalingfactor of 0 is assigned to the remaining channels.
 36. The method ofclaim 31, wherein the SNR improvement scaling factor of 1 is assigned tothe channel located within a predetermined distance from the touchposition, and the SNR improvement scaling factor of 0 is assigned to theremaining channels.
 37. The method of claim 31, wherein the SNRimprovement scaling factor which is assigned to each of the channels iscalculated based on a distance between the touch position and each ofthe channels, and wherein the distance between the touch position andeach of the channels is inversely proportional to the SNR improvementscaling factor which is assigned to each of the channels.
 38. (canceled)